useful

用作定語 ～+ n.

1. She's a useful person to know.
   她是個應該結交的有用的人。
2. John is a useful person to be around on such occasions.
   在這種場合有約翰在身邊是很有幫助的。
3. Horses are useful animals.
   馬是有用的動物。
4. I need a useful dictionary.
   我需要一本有用的詞典。
5. He gave us some useful advice.
   他給了我們一些有益的忠告。
6. Salt is a useful substance.
   鹽是一種有用的物質。
7. This is a useful book for beginners in English.
   這是一本對英語初學者有用的書。
8. The England cricket team scored quite a useful total.
   英格蘭板球隊得分總數令人滿意。

用作表語 S+be+～

1. Money is always useful.
   錢總是有用的。
2. Information about people's language ability is often very useful.
   有關人們語言能力的信息經常是很有用的。

S+be+～+ prep .-phrase

1. He is useful at cooking.
   他很會燒菜。
2. He is very useful at maths.
   他精通數學。
3. These books might be useful to you.
   這些書可能會對你有用。
4. These story books are useful to children.
   這些故事書對兒童有好處。
5. Your advice was very useful to me.
   你的勸告對我很有益處。
6. We should absorb whatever experience is useful to us.
   我們應吸取對我們有益的經驗。
7. Tom's advice has been most useful to us.
   湯姆的建議對我們是很有用的。
8. Such information is useful only to those who know that particular subject.
   這種材料只是對了解那個特殊問題的人才有用。
9. Outdoor sports are useful to your health.
   戶外運動對你的健康很有好處。
10. This book will come in useful for criticizing the wrong behaviour.
    這本書對批評錯誤的行為很有用。
11. The computer is useful in processing data.
    計算機在處理數據方面很有用。

It is/was+～+(for sb+) to- v

1. It is useful to read the text early in the morning.
   清晨讀課文很有用。
2. It is very useful for a person to know how to swim.
   對一個人來說會游泳是很有用的。
3. Probably it will be useful for them to acquire a practical knowledge of English.
   有英語的實際知識可能對他們有用。

It is/was+～+ v -ing

1. It's useful knowing several foreign languages when you are traveling abroad.
   在國外旅行時,會幾門外語是非常有用的。

用作賓語補足語 S+V+O+～

1. I find this pen very useful.
   我覺得這支筆很有用。