When they were served the ice cream 这是个什么时态的句子,是一般过去时吗可一般过去时不是直接served就行了,为什么还要加上 were
问题描述：
When they were served the ice cream 这是个什么时态的句子,是一般过去时吗
可一般过去时不是直接served就行了,为什么还要加上 were
答
When they were served the ice cream 意思是何时有人给他们提供了冰激 When they served the ice cream 意思是他们何时给别人提供冰激凌
前者是被动,被提供,也即有人提供
后者是主动,他们是提供者