形容詞 useful:

1. being of use or service
   同義詞：utile
2. having a useful function
   同義詞：utilitarian

1. 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。
2. It's more useful to learn modern languages, such as English and German, than Latin.
   學習英語和德語等現代語言比學習拉丁語更為有用。
3. 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。
4. This book is a storehouse of useful information.
   這本書里匯集了大量有用的資料。
5. He's a useful member of the team.
   他是該隊的一名強手。
6. This reference book is very useful to our study.
   這本參考書對我們的研究很有用。
7. She is a useful person to know.
   她是個應該結交的有用的人。