We don't go by air because we do not have enough money.
A.If we had enough money, we would go by air.
B.If we had had enough money, we would go by air.
C.If we have enough money, we will go by air.
D.If we had had enough money, we would have gone by air.

“If you don’t apologize, I’ll never speak to you again” he said.
A.He said if you don’t apologize, he’ll never speak to you again.
B.He said if I didn’t apologize, he would never speak to me again.
C.He said if I don’t apologize, he’ll never speak to me again.
D.He said if hadn’t apologized, he would never speak to me again.

If I weren’t so busy, I _____ go out with my friends.
A.would
B.wouldn’t
C.will
D.would have

If you _____ right now, you will be late for the train.
A.haven’t gone
B.didn’t go
C.hadn’t gone
D.don’t go

If she hadn’t been absent from school on Friday, she ______ what she had to do for homework.
A.will know
B.
C.won’t know
D.wouldn’t know

“You won’t get any better if you don’t practice your English” my teacher said.
A.My teacher told me you wouldn’t get any better if you didn’t practice your English.
B.My teacher told me I wouldn’t get any better if I didn’t practice my English.
C.My teacher told me you won’t get any better if you don’t practice your English.
D.My teacher told me I won’t get any better if I don’t practice my English.

The changes to the national health system will be ______ next year.
A.implemented
B.solved
C.met
D.done

One third of the world's population _______ two thirds of the world's resources.
A.absorbs
B.drains
C.consumes
D.supports

There is always a (an) ______ of water here in dry season.
A.shortage
B.weakness
C.inadequate
D.lack

We must limit population _________ because our resources are limited.
A.growth
B.grow
C.grown
D.growing