be 是英语中的助动词，用来构成各种时态，表示动作或状态的持续。它可以用来表示被动、完成、实施、完成等意思。在英语中，be 通常可以替换成其他动词，如have、do、show、seem、be about to等。例如：

He is being interviewed by the media.

She has finished her homework.

The meeting was cancelled because of bad weather.

The child is learning to speak Chinese.

He is going to be late for work.

She is looking forward to seeing you.

总之，be 是英语中非常常用的助动词，可以用来表示动作或状态的持续，同时也可以替换成其他动词来表示不同的含义。