这里class是课堂的意思，而且谓语动词是start动词原形，所以主语class要用复数。
My classes start on monday. I have to go.
我星期一开始上课，我得走了。
Before classes start up again, think about what you learned.
在课程开始之前，想想你学到了些什么。
Just you wait, when classes start next week, you\'ll be grateful.
只要等几天，当课程从下个星期开始时，你就会对此安排感激涕零。
