关于情态动词语法,语法书有个地方写need常用于疑问和否定句,在肯定句中用must,have to ,ought to

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关于情态动词语法,
语法书有个地方写need常用于疑问和否定句,在肯定句中用must,have to ,ought to ,should
但语法书有个地方介绍MUST的时候,有个句子MUST I BE HOME BEFORE TEN O'CLOCK?这不就是疑问句吗?为什么上面又说 need常用于疑问和否定句,按道理这是疑问句应该用need啊
到底是句子错了还是语法错了,

你的理解没有错.书上语法也没有错.must和need在必须意义上是一对.即肯定句用must do,否定句疑问句用need...do?needn't do...当然,must也可以直接提前构成疑问.但否定则必须使用needn't do了.此时need无三单和过去式变化.
I must be home before ten o'clock.
Must i be home before ten o'clock?yes,you must.no,you needn't.
Need i be home before ten o'clock?yes,you must.no,you needn't.
当need用于肯定句时,常可解释为需要,而不是必须.此时成为普通的实义动词.拥有三单和过去式变化了.但是不能再提前构成疑问,也不能+not构成否定了.要借助do了.
I need a book.Do you need a book yes,I do.No,i don't.
I need to have a rest.Do you need to have a rest Yes,i do.No,i don't.
your sock needs mending.Does your sock need mending Yes,it does.No,it doesn't.
He needed a book last night.Did he need a book last night yes,he did.No,he didn't.

关于情态动词语法,语法书有个地方写need常用于疑问和否定句,在肯定句中用must,have to ,ought to would ought to 作为情态动词通常用在肯定句疑问句还是否定句? 写情态动词have to的肯定句,否定句,一般疑问句, need作实意动词能用于否定句和疑问句吗?作情态动词能用于肯定句吗?举例说明关于情态动词和to我的一本语法书说情态动词除have和ought外,后面只能接不带to的不定式.可是后面又说带to的情用must,have to造句两个肯定句两个否定句一个一般疑问句并进行肯定和否定回答请问老师1.英语中need为何不能用于肯定句中作为情态动词,而可以用于否定和疑问呢? 情态动词的用法：must,can(could),may(might),ought to need,dare shall( 求need=n 的肯定句和否定句、need=to do 的肯定句和否定句、need doing 的肯定句和否定句求need+n 的肯定句和否定句、need+to do 的肯定句和否定句、need doing 的肯定句和否定句情态动词CAN情态动词can能用于表推测吗?怎么用?我的语法书上说：must+be+表语的结构表推测,他的否定和疑问形式在肯定句中,need可以做情态动词吗?