fall asleep与be asleep区别

题目

fall asleep与be asleep区别
①正在他们睡着的时候,听到了一些响声：翻译（用when还是while?、fall asleep还是be sleep?）
②be fall asleep是系表结构?fall asleep与be asleep 有没有正在进行时?如They are falling asleep/They are asleeping.

答案

fall asleep强调入睡的动作
be asleep 强调睡着的状态
意思都是入睡
例如：The baby is asleep,don't turn up the radio.
My father was so tired that he fall asleep quickly.