例句:Darwin thinks that natural selection is the chief factor in the development of species.
达尔文认为自然淘汰是物种发展中的主要因素。
2.get out of 逃避；避免
例句:It's amazing what people will do to get out of paying taxes.
人们为逃税而做出的种种事情令人吃惊。
3.at a time 一次；每次
例句:Can I borrow two books at a time?
我可以一次借两本书吗？
4.make up for 弥补
例句:Her beauty can't make up for her stupidity.
她的美丽不能弥补她的愚蠢。
