题干
250. Jack is a very stubborn(顽固的) person. I was unable to _____ him to do as I said. I want to ask you to have a word with him.
A：let
B：make
C：prevent
D：Persuade
答案(点此获取答案解析）
D
是偶函数，且
.若对任意的
，总有
，则
( )