It is a useful book and, what is more, not an expensive one.
这是有用的书, 更难得的是不贵。
It's more useful to learn modern languages, such as English and German, than Latin.
学习英语和德语等现代语言比学习拉丁语更为有用。
John always tries to cultivate people who are useful to him.
约翰经常设法和对他有用的人结交。
