用to bite off more than you can chew表达“自不量力”

成语 bite off more than you can chew 的意思是你不能正确估量自己的能力，对自己估计太高或承担超过自己所能胜任的事情。

• I have bitten off more than I can chew by taking on this extra work – I don‘t think I‘ll get it finished on time.
• David and Sarah planned to completely renovate their house by themselves. In the end, they bit off more than they could chew and had to pay builders to finish it.
• Thanks for offering to babysit AND cook dinner for us, but don‘t bite off more than you can chew.

值得注意的是，英语中的另一个同鳄鱼相关的短语是 crocodile tears 相当于汉语中的鳄鱼眼泪，恶人假慈悲。

• Louise is crying in the corner because she says the boss upset her – don‘t pay any attention to her, though – they‘re just crocodile tears.