Question

doing和be doing用法的区别（时态 语态上的区别）？

Answer 1

doing 和 be doing的区别是：

doing不能单独作谓语，但可以作主语、宾语、宾语补足语、表语、定语和状语。如：

Doing my homework took me 2 hours. （作主语）

I finished doing my homework at ten last night. （作宾语）

而be doing中的be是原形动词，可以根据不同时态进行变化，如：is／am／are doing（现在进行时）；was/ were doing（过去进行时）；will be doing （将来进行时），它们在句中充当谓语，如：

I was doing my homework when Mother came back.

Answer 2

doing 单独用时，是现在分词或动名词(这取决于在句中的功能)。

如: After doing his home work , he went on playing the game .

be doing 是谓语动词进行时态的结构。

如:

He was doing his homework last night .

Answer 3

doing 是do的动名词或者现在进行时态表达方法。be doing 就是某事正在发生的现在进行时表达方法。

Answer 4

doing，一个现在分词，不能做谓语。
be doing，现在进行时和过去进行时的构成，是做谓语的