useful

• 有用的人

  helpful person

• 有用的东西

  useful object

• 这本书我还有用。

  I'm still using this book.

• 他的主意对大家都有用。

  His ideas are useful for everyone.

• 这些资料别扔掉，将来还有用。

  Don't throw these materials away. They'll be useful in the future.