Stop dawdling and do something useful!

不要挨时间了， 做点有益的事吧！

《新英汉大辞典》

He studied something useful about the place.

他研究了一些关于这个地方有用的东西。

youdao

Do not idle about like this and do something useful.

别再这样闲混下去了，做些有益的事吧！

《新英汉大辞典》

At the end of the day this is all about equipping you with skills and knowledge and understanding with which to take a problem, take a large data set maybe and actually produce something useful-- produce a project that is of interest to you.

下午放学后,就用学到的技能，知识和理解力来,解决问题，或者处理超大数据集,或制造一些有用的东西-,例如发起一个你们感兴趣的项目。

哈佛公开课 - 计算机科学课程节选

You will find this pattern very useful anytime you're not feeling happy about something and you want to express yourself.

你会发现，当你因为什么事感到低落，你想表达自己的感觉时，这个句型特别有用。

I get so upset 课堂 - SpeakingMax英语口语达人

I think there is something useful about hearing the subject presented once orally.

我觉得亲自来这里,听一遍我讲的课是很有帮助的

耶鲁公开课 - 基础物理课程节选

But even when Ovshinsky creates something useful, he has no leverage to earn much from it.

FORBES: Magazine Article

These brands have failed to understand that apps are supposed to provide something useful.

FORBES: How To Make Amazing Branded Apps

Maybe Janet Reno's successor will do something useful and break up the local phone companies.

FORBES: Digital Rules