understand的用法有：

1、v.理解，知道，明白，懂得，领会 

例句：If you don' t attend to the lecture, you won' t understand.

如果你不用心听讲，你就不会懂。

2、听说，获悉，了解

例句：You understand the situation, I needn't elaborate any further.

你了解情况，我不需要再作详细说明了。

3、省略；推断 

例句：In the sentence `I can't drive', the object `a car' is understood.

在“我不会驾驶”这句话中，宾语“汽车”是不言而喻的。

4、make yourself understood（尤指用另一种语言）把自己的意思说清楚 

He doesn't speak much Japanese but he can make himself understood.

他不大会讲日语，不过尚能勉强表达意思。

5、give sb to believe/understand 使某人相信；使某人作…理解 

I was given to understand that she had resigned.

我得知她已经辞职了。