If you arrive at the office earlier than I do, please turn on the air-conditioner.
A.Were you to arrive at the office earlier than I do, you can turn on the air-conditioner.
B.Should you arrived at the office earlier than I do, you can turn on the air-conditioner.
C.
D.Had you arrive at the office earlier than I do, you could have turned on the air-conditioner.

Call your parents; otherwise, they will worry.
A.If you call your parents, they will worry.
B.If you didn’t call your parents, they would worry.
C.Were you to call your parents, they would worry.
D.Unless you call your parents, they will worry.

The police stopped him because he drove so fast.
A.If he had driven so fast, the police wouldn’t have stopped him.
B.If he hadn’t driven so fast, the police wouldn’t have stopped him.
C.Had he drive so fast, the police wouldn’t have stopped him.
D.If he didn’t drive so fast, the police wouldn’t stop him.

He was in a hurry. He wanted to catch the bus.
A.
B.He was in a hurry in order to he would catch the bus.
C.He was in a hurry seeing that catch the bus.
D.He was in a hurry despite catching the bus.

They weren’t happy because they were disappointed with the result.
A.They weren’t happy due to they were disappointed with the result.
B.They weren’t happy despite the fact that they were disappointed with the result.
C.They weren’t happy because of being disappointed with the result.
D.They weren’t happy although they were disappointed with the result.

Choose the sentence which has the closest meaning to the original one.I don’t know the answer, so I can’t tell you.
A.If I know the answer, I will tell you.
B.If I had known the answer, I would have told you.
C.If I knew the answer, I will tell you.
D.If I knew the answer, I would tell you.

If the tree weren’t so high, he could climb it up to take his kite down.
A.The tree is so high, he can’t climb it up to take his kite down.
B.
C.The tree isn’t so high, he could climb it up to take his kite down.
D.The tree wasn’t so high, could climb it up to take his kite down.

If you had driven more carefully, we wouldn’t have had that accident.
A.
B.Were you to drive more carefully, we wouldn’t have that accident.
C.Had you driven more carefully, we wouldn’t have had that accident.
D.Had you driven more carefully, we would have had that accident.

He had all the necessary books he doesn't use them to study.
A.Because he had all the necessary books, he doesn't use them to study.
B.Now that he had all the necessary books, he doesn't use them to study.
C.Even though he had all the necessary books, he doesn't use them to study.
D.Although he had all the necessary books, but he doesn't use them to study.

I forgot to keep the milk in the refrigerator, so it went bad.
A.The milk went bad because I forgot to keep it in the refrigerator.
B.
C.The milk went bad until I forgot to keep it in the refrigerator.
D.The milk went bad yet I forgot to keep it in the refrigerator.