bite off more than one can chew 好高骛远，不切实际，贪多嚼不烂，心有余而力不足，不自量力

　　Do your best. Do whatever you can but don't bite off more than you can chew.

　　尽最大努力，做你能做得到的事，但不要好高鹜远。

　　I think I bit off more than I can chew, when I decided to cook for the entire family.

　　我原本打算给全家人做一桌子菜，现在觉得这个想法有些不切实际。

　　疯狂练习吧！