他们正忙着做作业的英文是：They are busy doing their homework.
含作业的双语例句：
1、做了一下午作业，我想轻松一下。
Having done my homework for the whole afternoon, I want to ease up/I want to take my ease.
2、这个调皮的孩子根本无心做作业。
This naughty kid is completely uninterested in his schoolwork.
3、你们必须至迟在下星期五前交作业。
You must hand in your homework by next Friday at the latest.
4、他作业还没做完，无心去听音乐会。
He was in no mood to go to the concert, as he hadn’t finished his homework.
5、别挨时间了，睡觉前快把作业做完。
Stop dawdling and try to finish your homework before bedtime.
6、她先是完成了作业，接着又开始读书。
She finished her homework and then she started reading.
7、所有的书面作业都必须批分。
All written work has to be graded.
8、她轻松地完成了家庭作业。
She breezed through her homework.
9、那男孩只是随便把作业糊弄了一下完事。
The boy did his homework perfunctorily.
10、为了去看电影，小姑娘慌忙赶完了作业。
The little girl finished her homework in a great hurry so that she could go to the movie.
作业的用法：
作为名词时：
1、尤指艰巨或令人厌烦的任务，工作；
2、尤指语言教学中旨在帮助达到某一学习目的的活动；
作为动词时：
1、交给某人任务；
2、派给某人（工作）；
例：The student completed the task assign by his teacher.
学生完成了老师布置的作业。
Assignment.
释义：n.（分派的）工作，任务；（工作等的）分派，布置。
例句1：I have to finish this assignment.
译文：我得完成这作业。
例句2：I won't finish my assignment on time.
译文：我担心我不能按时完成我的作业了。
Responsibility.
释义：n.责任；负责；事故责任；职责；义务；任务。
例句：The responsibility naturally fell on our shoulders.
译文：责任自然地落到了我们肩上。