What do you mean by doing STH.?

你做某事是什么意思？

By doing STH, we become more and more sturdy and powerful.

通过做某事，我们变得越来越坚强和有力量。

It's + adj. + to do sth. ask sb. about sth. by doing STH. What's your favorite......? The best way to do STH.

做某事的……的。向某人询问某事通过做某事你最喜爱的……是什么？做某事的最好方式。

When I passed by his door, I heard him doing STH.

当我经过他的房门时，我听到他正在做某事。

Doing STH is by no means an easy thing.

做什么事绝不是件容易的事。