Question

usefulness n.有用，有益，有效;效能;

Accepted Answer

英[ˈju:sfəlnəs]  美[ˈjusfəlnɪs] ADJ-GRADED有用的；可用的；有助益的If something is useful, you can use it to do something or to help you in some way.例：The slow cooker is very useful for people who go out all day...慢炖锅对于整天都不在家的人来说很有用。例：Hypnotherapy can be useful in helping you give up smoking...催眠疗法可能有助于你戒烟。PHRASE有用；派得上用场If an object or skill comes in useful, it can help you achieve something in a particular situation.例：The accommodation is some distance from the clubhouse, so a hire car comes in useful.住处离会所有一段距离，所以租一辆车会很有用。

单词	usefulness
音标	英[ˈju:sfəlnəs] 美[ˈjusfəlnɪs]
解释	n.有用，有益，有效;效能;
例句	ADJ-GRADED 有用的；可用的；有助益的 If something is useful, you can use it to do something or to help you in some way. 例：The slow cooker is very useful for people who go out all day...慢炖锅对于整天都不在家的人来说很有用。例：Hypnotherapy can be useful in helping you give up smoking...催眠疗法可能有助于你戒烟。 PHRASE 有用；派得上用场 If an object or skill comes in useful, it can help you achieve something in a particular situation. 例：The accommodation is some distance from the clubhouse, so a hire car comes in useful.住处离会所有一段距离，所以租一辆车会很有用。
变形

例：The Usefulness 英[ˈju:Sfəlnəs 美[ˈjusfəlnɪs N.有用，有益，有效;效能 Adj Graded 有用的；可用的；有助益的 Slow