If he had (A) a (B) thorough knowledge of English, he could have applied (C) for (D) this post.
A.had (A)
B.a (B)
C.could have applied (C)
D.for (D)

If (A) her condition should (B) improve (C), we inform (D) you immediately.
A.should (B)
B.If (A)
C.improve (C)
D.inform (D)

I didn’t have enough money with me then; otherwise, I would buy that coat.
A.If I had had enough money with me then, I would have bought that coat.
B.If I didn’t enough money with me then, I would buy that coat.
C.If I didn’t enough money with me then, I wouldn’t buy that coat.
D.If I had enough money with me then, I wouldn’t buy that coat.

Plants and flowers can't live without water.
A.Unless you water plants and flowers, they live.
B.If you don't water plants and flowers, they can't live.
C.If you water plants and flowers, they can't live.
D.If you water plants and flowers, they will live.

Without this treatment, the patient would have died.
A.If there hadn’t been this treatment, the patient would have died.
B.Unless this treatment had been, the patient would die.
C.Unless this treatment, the patient will die.
D.If there weren’t this treatment, the patient would die.

Robert got a bad cough because he started smoking cigarette.
A.If Robert starts smoking cigarette, he won’t get a bad cough.
B.Unless Robert started smoking cigarette, he wouldn’t get a bad cough.
C.If Robert hadn’t started smoking cigarette, he wouldn’t have got a bad cough.
D.If Robert didn’t started smoking cigarette, he wouldn’t get a bad cough.

Stop talking or you won’t understand the lesson.
A.If you hadn’t stopped talking, you wouldn’t understand the lesson.
B.If you don’t stop talking, you won’t understand the lesson.
C.If you didn’t stop talking, you wouldn’t understand the lesson.
D.Unless you don’t stop talking, you won’t understand the lesson.

Our sources of energy will soon end if other sources are not found.
A.Unless other sources are found, our sources of energy will soon end.
B.Unless other sources are not found, our sources of energy will soon end.
C.If other sources are not found, our sources of energy will not soon end.
D.Unless other sources are were found, our sources of energy would soon end.

If you had known my dad, you would have thought he was wonderful too.
A.Know my dad, you would have thought he was wonderful too.
B.Had you known my dad, you would have thought he was wonderful too.
C.Have you known my dad, you would have thought he was wonderful too.
D.Had known my dad, you would have thought he was wonderful too.

It rained and we had to cancel the match.
A.
B.If it weren’t for the rain, we wouldn’t have to cancel the match.
C.Had it not been for the rain, we wouldn’t have cancelled the match.
D.Were it to rain, we wouldn’t have to cancel the match.