have sth done 让别人去做这件事,(某件事被做) e.g.I'll have my hair cut.我打算去理发. have sb do sth.让某人做某事,have是使役动词,后边要省略动词不定式to have sb doing sth.让某人持续做某事,强调"持续" e.g.He has us waiting for a long time. get sth done做完某事, get sb doing使某人正在做某事, get sb to do sth和have sb do sth意思可能相同,都是要求某人做某追问