conditionals: true, real and unrealalways true (zero conditional)il X happens, Y happensThese sentences describe what always happens in certain circumstances eg scientific facts.

present simple present simple

When / Jf you press the switch, the light comes on.

real conditions (conditional 1)if X happens, Y will happenThesesentencesdescribewhat the speaker thinks will possibly happen asa consequence of a real situatior

present simple will future

Jf we do not deal with the global warming problem, temperatures will rise.

If we leave now, we'lI catch the bus. If we don't leave now, we won't catch it.

In informal speech, we often use going to instead of will.If you don't take an umbrella, you're going to get wet.We also usemight or can / could in place of will. SeeUnit 25

We can also use imperatives in real conditions.If you don 't knowa word, look it up in the dictionary

Sentences beginning Jf you will ... are only usedwhen will means insist, or is used as a polite form.If you will stay up 50 late, then of course you'll feel tired. (insist)If you'lI wait here, I'/Isee if the manager is ready (polite)

unfessUnless means only if not. We use it when we say that if something does not happen,something else will happen.

Unless we deal with the global warming problem, average temperatures will rise.

provided, as fong as + present simpleProvided and as long as mean only if.

Provided / as long as we reduce energy consumption, we can slow down global warming.

in case + present simpleThis describes a possible situation we want to be prepared for.

Takean umbrel/a in case it rains.

unreal conditions (conditional 2)if X happened, Y would happenThese sentences describe what the speaker thinks would happen in an imaginary situation.

past simple would + verb

fi

If you were on Venus, you would see the Sun rise in the west.·1·

What would happen if the Earth stopped turning?If the Earth didn't have a Moon, there wouldn't be any tides.

The past simple tense we use in an if-sentence does not describe past time, but unreal time.We also usemight or could in place of would. SeeUnit 25.

if f were youWe give advice with If I were you.

I wouldn't do that, if I were you. ar If I were you, I wouldn't do that.

 

-eal or unreal?;'is depends on the situation of the speaker, or what the speaker is thinking.For example, we're in the classroom. There are some heavy tables. I think a friend is going to liftthem. I give a warning.'Ii you try to lift those tables on your own, you'lI hurt yourself '

Samesituation. Nobody is thinking of lifting the tables. I make a comment.Those tables look heavy' li you tried to lift them, you'd hurt yourself'

Complete the answers using the word or words in capitals.

a What happens when you heat water to 100°C?If you ..h~alLAJale.rlDIOO°c, ..ilboiIS

b What does water tum into when you boil it?If you

c What happens when you cool the steam?If you

d What happens when you heat a piece of metal?Ifyou ..

e What happens when you freeze a piece of metal?Ifyou

f What happens when you freeze water?If you . . . ..

BOIL

STEAM

TURNSBACK

EXPANDS

CONTRACTS

EXPANDS

2 Use the words to complete an if-sentence about solutions to environmental problems.

Solution A - recycle paper, metal and glass

a everyone / recycle paper / companies / not cut down so many treesl'+.~V~rtjovt~..r~ct:Jd~S ..pap~r, ..coMpt1\'J.i~S..LAJD\'J.)l..cul ..dOLAJvtSD..Ma\'J.'1..lr~e5, .

b everyone / recycle metal and glass / we not waste valuable resources

c everyone / recycle paper, metal and glass / we not produce so much rubbish

Solution B - tum oft lights, don 't drive 50 much, insulate your house

d everyone / tum off unwanted lights / save a lot of electricity

e everyone / walk or cycle / not waste so much oil and petrol

f everyone / insulate their houses / not waste so much energy for heating

Solution C - use renewable energy

g countries use more wind and wat er power, not depend so much on power stations

h countries use power stations less, cause less air pollution

rea;l-C:::::s

"'OCre

rea;l-a;":::::sl-+-'V'l

reCO+-'"'OCOuG

 

3 Use the prompts to complete the question.Then choose the most likely answer.Check the factual answers on page 208.

a what / happen if you / travel through theEarth to the other side?

...tl}hal. ...wQuld..harp~Yl ..if.'1ou ..l.raveAI~d ......l.hrQuqh ..l.he, ..~arl.h ..l.o.l.he, ..Ql.he,c....sidd ..

b what / happen if the Earth suddenly stop/ going round?

G

c what / happen if we not / have a Moon?

d what / happen if a11the ice at the poles / melt?

e what / happen if there be / no more electricity?

t what / happen if aliens receive / messages from Earth and decide / to visit us?

a A Yau wauld f/y aut the B This wauld be impassibleC Yau wauld (all ta the centre

ather side inta space.

because the Emth's core is hat.and then stap.

b A We wauld enjay langer

B It wauld stmt maving in theC Even i( the Earth stapped, we

and warmer days

appasite directianwauld keep maving!

c

A There wauld nat be any B The Earth wauld spin mareC The Sun wauld graw stranger.acean tides.

slawly

d A Sea levels would (all.

B Sea levels wauld stay the same.C Sea levels would rise.

e A The universe wauld na

B People would use candles (orC The world would be a sa(er

longer exist.

light and fires (or heat.place.

tA They wouldn't know B They wauldn 't arrive (orC They wouldn't understand

exactly where we were.

millians o(years, as theyour messages anyway.would be so (ar away. ~

4A Rewrite each sentence so that it contains unfess or as fong as and begins as shown.

a Ii you don't tra in hard, you won't succeed in sport.You wonll. ..suc,ce,e,d..iY\ ..spQcl !,J,YlI~SS..t:lQulcaj!'\ ..hard .

b Ii you train regularly, you can improve YOllI performance.You can improve ..

c Ii you enjoy YOllI sport, it doesn't rea11ymatter whether you succeed or not.It doesn't rea11ymatter ..

d Ii you don't eat and sleep properly you won't develop as an athlete.You won't ..

                             

B Rewrite each sentence 50 that it contains in case.

e Take a spare pair of running shoes, because it's possible that you will need them.Take a spare pair of running shoes .

f Take a waterproof coat with you because it's possible that it will rain.Take a waterproof coat with you ..

g take a warm jumper because it's possible that you will get cold when you stop.Take a warm jumper ..

h Take a first-aid kit because it's possible that someone will get injmed.Take a first-aid kit

5 Use the words to complete the conditional if-sentence. Use an always true, real or unrealconditional to suit the meaning.

a Scientists are planning a way of writing extremely smallletters, using xenon (Xe) atoms. Ifyou (use)4S.e-,L this system, you (be able) to write ten copies of theBibIe on the area of a postage stamp.

b Humans are among the few animals to have colom vision. If you (be) a horse,for example, you (see) everything in black and white.

c The brain works in two parts, the left side and the right side. Scientists can put one side ofthe brain to sleep, and see what happens. For example, if they (tum off) theright side of the patient's brain, the patient (not be able) .... ....to sing, becausemusical ability comes from the right side of the brain.

d Beetles are one of the most numerous species on the planet. In fact, if other insects andanimals (not eat) .. ... beetles, in about a year and a half the beetle population(weigh) .. . as much as the whole Earth!

e Parts of the body send messages to other parts of the body when they have to do things.For example, if you (not have) .... enough water in yom body the brain (let)

..you know that you need more, by making you feel thirsty.f If you (look) .. . inside yom own eye at the images there, they (be) ..upside down, and they (be) ... ..moving.

g If you (smoke) .. .., chemical changes (take place) in yom cells,which do not receive enough oxygen and die.

h The world's oceans contain huge amounts of salt. In fact, if you (remove) ... . all thesalt from the oceans, you (be able) to use it to build a wall about 300km wide anda kilometre tall all around the Earth!

= . ·EXTE~Slcg'N·tAf]?I\i!.j~~t=~h~tl.;D~"_......·c1 Write five sentences about your life which begin Un/ess I ...

2 Write a list of eight interesting scientific factsyoufound in this unit, which begin If ...Need more practice? Go to the Review on page 792.

coOJl....C::::l

"'OCCO

COOJl....

OJ~::::ll....+-'V\COCO+-'"'OCOufa

          KEY          

                                       

                               

Ex4a The teacher told John to the fill the jar with water.b The teacher asked Angela to help him. c Theteacher told Michael not to spill the water. d Theteacher asked Alison if she would pour / to pour alittle water into the test tube. e The teacher toldSteve to light the gas. f The teacher told Alan notto touch it with his finger. g The teacher toldSarah to heat the water gently until it boiled. hThe teacher asked all of them to watch the watercarefully.

Ex 5

al b8 (7 d6 e2 f4 g3 h5

Ex 6Suggested answers: a said his advice was b told,to choose a workout c told /advised them / theaudience to avoid activities that were d suggesteddoing it a bit difterently each time e explained thatmaking sure you have f wamed that overtrainingcan g reminded them / the audience to eat h saidthey / the audience shouldn't use

Unit 18Ex 1a If you heat water to 100°C, it boils.b If you boil water, it turns into steam.c If you cool the steam, it turns back in to waterd If you heat a piece of metal, it expands.e If you freeze a piece of metal, it contracts.f If you freeze water, it expands.

Ex 2

a If everyone recycles paper, companies won't cutdown so many trees. b If everyone recycles metaland glass, we won't waste valuable resources. cIfeveryone recycles paper, metal and glass, we won'tproduce so much rubbish. d If everyone turns oftunwanted lights, we will save a lot of electricity.e If everyone walks or cycles, we won't waste somuch oil and petrol. f If everyone insulates theirhouses, we won't waste so much energy for heating.g If countries use more wind and water power, theywon't depend so much on power stations. h Ifcountries use power stations less, they will cause lessair pollution.

Ex 3

a What would happen if you travelled through theEarth to the other side? b What would happen ifthe Earth suddenly stopped going round? c Whatwould happen if we didn't have a Moon? d Whatwould happen if all the ice at the poles melted?e What would happen if there was no moreelectricity? f What would happen if aliens receivedmessages from the Earth and decided to visit us?

Ex4Aa You won't succeed in sport unless you train hardob You can improve your performance as long as youtrain regularly. ( It doesn't really matter whetheryou succeed or not, as long as you enjoy your sport.d You won't develop as an athlete unless you eat andsleep properly.

Ex4Be Take a spare pair of running shoes in case youneed them. f Take a waterproof coat with you incase it rains. g Take a warm jumper in case you getcold when you stop. h Take a first-aid kit in casesomeone gets injured.

Ex 5

a used, would be able b were, would seec tum off, won't be able d didn't, would weighe don 't have, willlet f looked, would be, would beg smoke, tak e place h removed, would be able

Unit 19Ex 1a had marched, would have conquered b hadgone, would have succeeded ( had built, wouldhave crossed, (would have) landed d had not hit,would not have arrived e had continued, wouldhave sailed f had not read, would not have triedg had sailed, would have reached h had notthought, would not have conquered i had notfound, would not have made j had not taken,would not have written

Ex 2

Suggested answers: a If I hadn't brought a map withme, we would be lost. b If I hadn't explained mynew ideas to the Church, I wouldn't be in trouble.c If I hadn't exaggerated some of the descriptions inmy book, perhaps more people would believe me.d If we hadn't gone to the theatre last night, hewould be alive today. e If I had spent more timeon my painting, more of them would be finished.f If I hadn't invaded Russia, I would still be Emperorof France.

Ex4a The teacher told John to the fill the jar with water.b The teacher asked Angela to help him. c Theteacher told Michael not to spill the water. d Theteacher asked Alison if she would pour / to pour alittle water into the test tube. e The teacher toldSteve to light the gas. f The teacher told Alan notto touch it with his finger. g The teacher toldSarah to heat the water gently until it boiled. hThe teacher asked all of them to watch the watercarefully.

Ex 5

al b8 (7 d6 e2 f4 g3 h5

Ex 6Suggested answers: a said his advice was b told,to choose a workout c told /advised them / theaudience to avoid activities that were d suggesteddoing it a bit difterently each time e explained thatmaking sure you have f wamed that overtrainingcan g reminded them / the audience to eat h saidthey / the audience shouldn't use

Unit 18Ex 1a If you heat water to 100°C, it boils.b If you boil water, it turns into steam.c If you cool the steam, it turns back in to waterd If you heat a piece of metal, it expands.e If you freeze a piece of metal, it contracts.f If you freeze water, it expands.

Ex 2

a If everyone recycles paper, companies won't cutdown so many trees. b If everyone recycles metaland glass, we won't waste valuable resources. cIfeveryone recycles paper, metal and glass, we won'tproduce so much rubbish. d If everyone turns oftunwanted lights, we will save a lot of electricity.e If everyone walks or cycles, we won't waste somuch oil and petrol. f If everyone insulates theirhouses, we won't waste so much energy for heating.g If countries use more wind and water power, theywon't depend so much on power stations. h Ifcountries use power stations less, they will cause lessair pollution.

Ex 3

a What would happen if you travelled through theEarth to the other side? b What would happen ifthe Earth suddenly stopped going round? c Whatwould happen if we didn't have a Moon? d Whatwould happen if all the ice at the poles melted?e What would happen if there was no moreelectricity? f What would happen if aliens receivedmessages from the Earth and decided to visit us?

Ex4Aa You won't succeed in sport unless you train hardob You can improve your performance as long as youtrain regularly. ( It doesn't really matter whetheryou succeed or not, as long as you enjoy your sport.d You won't develop as an athlete unless you eat andsleep properly.

Ex4Be Take a spare pair of running shoes in case youneed them. f Take a waterproof coat with you incase it rains. g Take a warm jumper in case you getcold when you stop. h Take a first-aid kit in casesomeone gets injured.

Ex 5

a used, would be able b were, would seec tum off, won't be able d didn't, would weighe don 't have, willlet f looked, would be, would beg smoke, tak e place h removed, would be able

Unit 19Ex 1a had marched, would have conquered b hadgone, would have succeeded ( had built, wouldhave crossed, (would have) landed d had not hit,would not have arrived e had continued, wouldhave sailed f had not read, would not have triedg had sailed, would have reached h had notthought, would not have conquered i had notfound, would not have made j had not taken,would not have written

Ex 2

Suggested answers: a If I hadn't brought a map withme, we would be lost. b If I hadn't explained mynew ideas to the Church, I wouldn't be in trouble.c If I hadn't exaggerated some of the descriptions inmy book, perhaps more people would believe me.d If we hadn't gone to the theatre last night, hewould be alive today. e If I had spent more timeon my painting, more of them would be finished.f If I hadn't invaded Russia, I would still be Emperorof France.