go to bed　go to sleep　get to sleep　fall asleep　be asleep
　　首先应知道sleep是动词,asleep是形容词。
　　⑴ go to bed指上床, 就寝。例如:
　　What time did you go to bed last night?
　　昨天晚上你几点上床睡觉的?
　　⑵ go/get to sleep和fall asleep意思接近,都指入睡,睡着, 但是get to sleep常用于否定句中。例如:
　　I went to sleep quite late last night.
　　我昨晚睡着很晚了。
　　⑶be asleep指睡着的,睡熟的。例如:
　　He is asleep.
　　他睡着了。