被动语态

当主语是动词所表示动作的承受者时，应当使用被动语态，所以被动语态通常强调动作的承受者。

使用场景

1. 当动作的承受者更为重要时
2. 当动作的发出者不明确或不重要时
3. 在一些科学文献中

一般现在时

am/is/are (not) + 过去分词

1. Butter is made from milk.
2. How often are these rooms cleaned?

一般过去时

was/were (not) + 过去分词

1. We weren't invited to the party last week.
2. Was anybody injured in the accident?

I was born

描述出生一般使用I was born而不用I am born，因为出生的动作已经发生。

Where were you born?

现在进行时

is/are being + 过去分词

1. The door is being painted
2. The office is being cleaned at the moment.

现在完成时

has been done

1. The door has been painted.
2. I haven't been invited.

被动语态 + by

by 通常用于引出动作的发出者。

The telephone was invented by Alexander Bell in 1876.