如何理解非谓语动词的语态
一、总的使用原则
若非谓语动词与其逻辑主语为主动关系，就用主动形式；若非谓语动词与其逻辑主语为被动关系，就用被动形式。如：
I like watching others working. 我喜欢看别人干活。
I don’t like being watched. 我不喜欢被人盯着。
You should send someone to repair it. 你应将人去修好它。
You should send it to be repaired. 你应将它送去修理。
Without anyone noticing, he slipped through the window. 无人注意，他从窗户溜了出去。
Not being seen by anyone, he slipped through the window. 他趁无人看见时从窗户溜了出去。
二、值得注意的问题
在某些特殊句式中，非谓语动词可以用主动形式表示被动意义。如：
那个节目是不值得观看的。
误：That program isn’t worth being watched.
正：That program isn’t worth watching.
那样的问题有时很难回答。
误：Such questions are some times difficult to be answered.
正：Such questions are some times difficult to answer.