before 用作连词时、后接从句 什么时候+doing 、什么时候+过去分词1.Li Lei often smiles at me before ____( talk) to me.2.Mr.Smith can buy a small present before ____(invite) to a party.写出答案、并说明原因 、讲解 .(最好通俗易懂 )

问题描述:

before 用作连词时、后接从句 什么时候+doing 、什么时候+过去分词
1.Li Lei often smiles at me before ____( talk) to me.
2.Mr.Smith can buy a small present before ____(invite) to a party.
写出答案、并说明原因 、讲解 .(最好通俗易懂 )

1)talking,这里省略了主语he,完整的句子是before he talks to me.talk在完整的句子中用的是主动语态,所以省略主语的时候要将动词形式变为doing的形式.
2)invited,这里省略了主语Mr.Smith,完整的句子是before he was invited to a party.invite在完整的句子中用的是被动语态,所以省略主语的时候要将动词形式变为过去分词的形式.