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,
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...