做助动词:
疑问句:把have提前,如Have you been there before? Have you done your homework?
否定句,变have为haven't 。
情态动词
疑问句:用Do提问,如Do you have to do this right now? Does Tom have to go to school?
否定句:加don't,如I don't have to do it now. Tom doesn't have to go to school today.
做“有”讲的时候,和一般动词用法相同。
我知道的就是这些,希望能对你有帮助。