被动语态 使用场合

不清楚或没有必要说明动作的执行者是谁。

强调动作的承受者，而不强调动作的执行者。

Some new computers were stolen last night.

The biggest apple is eaten by his brother.

处于礼貌、婉转等避免说出动作执行者。

You'll be contacted. Visitors are required not to pick flowers.

避免更换主语，以求行文流畅。

The professor came in and was warmly welcomed.（连贯） The professor came in and we welcomed him warmly.（不连贯）