Exercise 6: Choose the best answer for each of the following sentences.
1.    _____have enough apples, she’ll make an apple pie this afternoon.
A.Should she        B. If she        C. Will she        D. Unless she
2.    If you_____to me, you wouldn’t have got so much trouble.
A. listened            B. would listen    C. had listened        D. Would have listened
3.    If you don’t know how to spell a word, you_____ look it up in the dictionary.
A. must            B. will            C. should        D. ought
4.    If the sun _____, we _____for a walk.
A. shines / will go        B. shone / will go    C. shone / would go    D. had shone / would go
5.    The campfire _____ if it _____ last night.
A. wouldn’t be cancelled / hadn’t rained        B. wouldn’t have been cancelled / hadn’t rained
C. would have been cancelled / hadn’t rained    D. will be cancelled / rains
6.    But for our parents, we _____ successful in life.
A. will never be        B. would never be    C. wouldn’t have be     D. would have never been
7.    If I _____ my wallet at home this morning, I _____ money for lunch now.
A. leave / will have                B. didn’t leave / would have
C. hadn’t left / would have            D. hadn’t left / would have had
8.    It is too bad, Lam isn’t here. If he _____ here, he _____ what to do.
A. were / would know                 B. is / will know        
C. had been / would have known            D. was / would know
9.    If we _____ the plans carefully, we would not have had so many serious mistakes.
A. study        B. had studied        C. studied        D. were studying
10.    I will never talk to you again _____ you apologize me _____ your being rude.
A. if / for        B. unless / for        C. or / of        D. whether / or
11.    _____ if you work harder, you will be sacked.
A. Whether    B. If            C. However        D. Unless
12.    I think you should stop smoking.
A. If I am you, I will stop smoking.    B. If I were you, I will stop smoking.
C. If I were you, I would stop smoking.    D. If I had been you, I would stop smoking.
13.    If you take the ice out of the fridge, it _____.
A. vaporizes    B. melts        C. heats        D. disappears
14.    We should do something to protect water from being polluted _____we will have nothing to drink in the future.
A. if        B. whether        C. or            D. unless
15.    Let’s knock on their door to see _____ home.
A. if they’re        B. unless they’re        C. whether they were        D. if they were
16.    Unless we _____  more snow, we can’t go skiing.
A. will have        B. have            C. have had            D. had
17.    You’ll fail the exam _____ you start revising.
A. if            B. until            C. when            D. unless
18.    Unless you wash the car, you _____ not drive it at the weekend.
A. would            B. could            C. have to            D. may
Dạ mn cố gắng xong trc 10h40 giúp mình với ạ, mình gấp lắm rồi ạ