1.stop to do sth. 和stop doing sth.

　　“stop to do sth.” 表明停止做其它工作而去做“to do sth.”所表明的工作，能够将“to do sth.”了解成“stop”的意图状语：“stop doing sth.”表明不做“doing sth.”所表明的工作。

　　例如：“Stop talking. Let's begin our class.”said the teacher. 教师说：“别说话了，让咱们开始上课。”

　　We have kept doing our homework for a long time. Let's stop to listen to music. 咱们做家庭作业很长时间了，让咱们停下来听听音乐。

　2.have sth. done.(过去分词)(让他人)做某事

　　例如：I had my hair cut yesterday afternoon. 我昨天下午理了发。

　　My computer can not work now. I must have it repaired. 我的电脑有故障了，我必须让人修好它。

　3.forget to do sth.和forget doing sth. (remember to do sth. 和remember doing sth.)

　　“forget to do sth.”表明将来不要忘掉做某事，谈的是将来的工作：“forget doing sth.”表明忘掉过去应当做的工作。

　　例如：“Don't forget to do your homework.”said the teacher before the class was over.

　　教师在下课前说：“不要忘掉做家庭作业。”

　　“I'm sorry. I forgot doing my homework. May I hand it in this afternoon，Mr. Chen?”said Li Ming.

　　李明说：“对不住，我忘掉做家庭作业了。我今天下午交好吗，陈教师?”