1.have sb/sth do sth 使得某人/物做某事
要求：宾语sb/sth和宾语补足语动词do之间是主动的关系,且do sth所表示动作一般未发生,或只强调动作本身.
如果句子变成被动语态时,to必须要补上.
如：I'll have Tom undertake this task.
Don't have the machine run when you leave.
2.have sb/sth doing sth 使得某人/物一直/总是做某事
要求：宾语sb/sth和宾语补足语动词do之间是主动的关系,且do sth所表示动作一直在发生,后面一般会加上表示时间段的短语.
如：The teacher has his students doing homework the whole afternoon.
Don't have the machine running all the time.
3.have sb/sth done 使得某人/物被...
要求：宾语sb/sth和宾语补足语动词do之间是被动关系.
如：I'll have my hair cut tomorrow.
You can't have your son beaten by others children.