The house looked as if it was about to fall down.
房子看起来好像就要倒塌似的。
If the blocks are placed off-centre, they will fall down.
积木如果搭得中心错位就会倒塌。
Babies often fall down when they are learning to walk.
小儿学步时常会跌交。
There's nothing to be afraid of. The sky won't fall down.
没有什么好怕的`，天不会塌下来。
You are likely to fall down on your research project if you don't go to the experts for advice.
如果你不去向专家们请教，你的研究项目很可能夭折。