have to do sth句型所表达的汉语意思，学习过英语的人都知道。不就是表示“不得不做某事”嘛！而且带有“强调客观条件”的感情色彩。然而，对其否定式和疑问式的表达方式，也许学习的稀里糊涂！因为在某些辅导初中生学习英语的报刊上，经常有这样的辅导：have to do sth的否定式和疑问式必须使用助动词do来完成，其否定式为don't / doesn't have to do sth(第三人称单数主语用doesn't，其他人称主语用don't)；其疑问式是在第三人称单数主语前加does，在其他人称主语前加do。以此片面观点，出现过下面的中考题：

         1、Lucy has to do her homework now, _______?(2001??市)

              A、 has she       B、hasn't she        C、do she        D、doesn't she

         2、 He had to give up halfway because of snowstorm.  (改成反意疑问句)(2002年？？市？？区)

               He had to give up halfway because of snowstorm, ________  ________?

         3、Meimei has to look after  her little brother at weekends.  (改成一般疑问句) (2003？？市)

              ______Meimei______ to look after her littl brother at weekends?

         4、He has to buy a dictionary for his daughter.  (改为否定句) (2003？？省)

              He ______  _____ to buy a dictionary for his daughter.

        例1给出的答案是D，然而A和B也都是正确答案。例2给出的答案是didn't he，然而，本题客观上还存在着 did he， hadn't he和 had he这样三个正确答案！但表达的语义各不相同。例3给出的答案是Does...have，例4的答案是doesn't...have，同样，此二题都还有另外的正确答案存在！因为have to do sth 的否定式和疑问式不使用助动词do的形式也是正确的！请看出自《牛津现代高级英汉双解词典》（商务印书馆，牛津大学出版社）中对此句型的解释：

      “have3: vt (Used in the neg and interr with or without the aux v "do". The distinction is not always clear and  there can be recommendations only, not rules. When  the reference is to sth regular or habiyual, the use of do for neg and interr is to be preferred. When the reference is to a particular occasion, constructions without do, and, in colloq style, with got, are to be preferred.）（用于否定和疑问句时，用助动词do 或不用皆可。用do与不用do的区别不太明确，并无规则可循，仅有下列的提示可供参考：指通常或习惯上的动作时，在否定或疑问句中多用do；指一特殊事例时，多不用do，并且在口语中多与got 连用。”（P529) 同时，该词典中也给出了下面的例子：

        Do you often have to go to the dentist's?   你必须常常去看牙吗？

        Have you (got) to go to the dentist's today?   你今天必须去看牙吗？

        The children don't have to go to school on Sundays, do they?  孩子们星期天不须上学，是吗?

        You haven't (got )to go to school today, have you?  你今天不须去上学，是吗？

        Had you  / Did you have to leave early?  你必须早些离去吗？