The master had commanded his servants, of course, to do something - to show a profit in a due and timely fashion, but Milton wants his friend here to know that there's, of course, nothing to worry about.

主人要求他的仆人，适时的,展示出自己的利润，弥尔顿希望，他的朋友知道。

耶鲁公开课 - 弥尔顿课程节选

because it's something that will help you master English step by step.

因为它能够帮助你一步一步地掌握英语口语。

have to 课堂 - SpeakingMax英语口语达人

It's very easy to use. But something you really should master.

这个句型很容易就能学会，这也是你必须得掌握的一个句型。

When 课堂 - SpeakingMax英语口语达人