The challenge is for the work you are going to be doing at the class time we are doing to spend together.

这一挑战是针对,我们要一起在课上,完成的任务提出的。

麻省理工公开课 - 媒体、教育、市场课程节选

It's got exercises for you to do so at the end of each chapter, you do have a task to do.

里面为你准备了练习，所以在每章的结尾，你都有任务要完成。

英语写作：技巧 - SpeakingMax英语口语达人