重点讲解：
1. find out (尤指特意通过努力)发现，找出，查明；
例句：It is a matter of the utmost urgency to find out what has happened to these people.
当务之急是要弄清楚这些人出了什么事RZ*Em1X-27o!F。
2. in general 总的来说；总体上来看；大体上；
例句：In general her work has been good,but this essay is dreadful.
总的说来，她的作品不错，不过这篇文章糟透了0)2XOqFqd9IlFAxKZ5。
3. fall behind 落后；跟不上；
例句：If you don't come to class regularly, you will fall behind in your studies.
如果你经常不来上课，学习成绩就会落在别人后面NINNmHPs&x(LH。
4. keep sb. on sb.'s toes 使保持警觉；
例句：Nobody likes uncertainty, but it does keep you on your toes.
没有人喜欢不确定的事，但它的确会使你保持警觉Mkr+~R8)gsuQZ=w%l。