The house looked as if it was about to fall down.

　　房子看起來好像就要倒塌似的。

　　If the blocks are placed off-centre, they will fall down.

　　積木如果搭得中心錯(cuò)位就會(huì)倒塌。

　　Babies often fall down when they are learning to walk.

　　小兒學(xué)步時(shí)常會(huì)跌交。

　　There's nothing to be afraid of. The sky won't fall down.

　　沒有什么好怕的，天不會(huì)塌下來。

　　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?qū)＜覀冋?qǐng)教，你的研究項(xiàng)目很可能夭折。