The newsletter is a useful channel of communication between teacher and students.

发简讯是沟通师生的有益渠道。

《牛津词典》

youdao

They are also becoming a useful tool for firefighters, helping them find and fight wildfires.

它们也正在成为消防员的一个有用工具，帮助他们发现和扑灭野火。

youdao

They created Pedal People as a way to create a useful service that helps the local economy and is environmentally friendly.

VOA: special.2009.12.04

We are talking about a society,therefore, the anthropologists have come up with, which I think is a useful distinction.

因此,我们所说的这个社会是一个...,人类学家已经提出了一种区分的方法,我认为很有用

耶鲁公开课 - 古希腊历史简介课程节选

And it's a useful pattern when you want to express that your feelings have been hurt or that you're not liking something,

当你想表达你在情感上受到了伤害或者不喜欢某件事的时候，这是个很有用的句型。

I get so upset 课堂 - SpeakingMax英语口语达人

Scouring stores for a useful toy, the father became as frustrated as his son.

FORBES: Anything But Child's Play

But unlike culture at large or "the Internet, " Facebook created a useful mechanism for change.

CNN: Facebook rejects rape culture. Can you?

This is a useful book for people looking to start a professional speaking career.

FORBES: Resolved to Start a Speaking Career in 2012? A Roundup of Recent Books To Help You Get Cranking