英语四级英语语法知识，在*，独立调查的题基本上沒有，可是语法知识点却围绕一整张考卷，下边是我为大伙儿梳理的专业知识，期待能够为大伙儿产生协助，一起来学习培训一下吧。
　　 21.4 较为have to和must
　　1)两词全是'务必'的含意，have to 表明客观性的*须， must 表明讲话人主观性上的观点，既主观性上的必需。 My brother was very ill, so I had to call the doctor in the middle of the night.我弟弟病得很厉害，我只能大半夜把医师找来。(客观性上*须做这件事情) He said that they must work hard. 他说道她们务必认真工作。(主观性需要做这件事情)

　　2)have to有些人称、数、语态的转变，而must仅有一种方式。但must 可用以间接引语中表明以往的必需或责任。 He had to look after his sister yesterday.
　　3) 在否认构造中： don't have to 表明"无须" mustn't表明"严禁"， You don't have to tell him about it. 你没一定要把这事对他说。 You mustn't tell him about it.你一定不必把这件事情对他说。