Exercising is good for us和 Reading in bed is bad for your eyes.Exercising和Reading为什么要加ing.

问题描述:

Exercising is good for us和 Reading in bed is bad for your eyes.Exercising和Reading为什么要加ing.

为了表示做某件事、前方都加ing 、用这件事来说明那件事怎样怎样的。

doing做名词
动名词

exercise ,read都是动词,动词只能做谓语,这里要它们作主语,要把它们变为动名词的形式