d,for bed
这是固定用法：It's time for sth.意为：该是去xxxx的时候了
(又It's time for bed = It's time to go to bed.)
所以应该选D
D.
To 后面是要加动词的,所以a,c就都不对了,bed是名词（作动词时就不是睡觉的意思）,asleep是形容词.
For 后面是要加名词,所以B也不对,就只有D了