4.情态动词：can(could),may(might),must,shall(should)等等
She turned off all the lights which had been left on. 她关掉了所有还在亮着的灯。
②如果宾语是人称代词，只能放在动词和副词之间。
She gave them away.她送掉了它们。
③同一动词和不同副词搭配时，意义上有很大的差异。
ring back回电话, ring off挂断电话, ring up打电话
put away放好, put on穿，上演, put up挂起，举起。
