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 ...