useful用作形容詞的用法例句

　　It is a useful book and, what is more, not an expensive one.這是有用的書，更難得的是不貴。

　　The book contains much useful information.這本書包含了許多有用的資料。

　　John always tries to cultivate people who are useful to him.約翰經常設法和對他有用的人結交。