选择适当的词语替换句中的画线部分。
1. By the time he got home, his parents had slept.
A. Before
B. As soon as
C. When
D. While
2. The alarm clock didn't go off this morning.
A. ring
B. set off
C.ring up
D. call
3. We felt very exhausted.
A. embarrassed
B. tired
C. bored
D. relaxed
4. We convinced him there was no danger.
A. thought him
B. made him know
C. made him believe
D. discovered
5. Mr Li rushed to the boy and saved him.
A. ran
B. spoke quickly
C. drank fast
D. moved quickly