Ⅰ. asleep adj “睡着的”;常作表语。如：
① The children have been asleep.孩子们已睡着了。
② He was too tired and fell asleep at once. 他太累了，立刻就睡着了。
Ⅱ. sleep v & n “睡着”。如：
① You have a good sleep. 你需要好好睡一觉。
② Last night I sleep very well. 我昨天晚上睡得很好。
Ⅲ. sleepy adj “困乏的、想睡的”。如：
① She is always sleepy. 她总是想睡觉。
② I feel very sleepy now. 我现在昏昏欲睡。