need？和must？都意味着说话的对方是有关的权威。need？还包含着说话人希望得到否定回答的含义：Must I go，moth- er？和Need I go，mother？含义相同，但在后一问句中，说话人希望他的母亲回答说不”。need的另一种疑问式do I need？等也有同样的用...
A1 如前所述，need not表示说话人的权威或劝告：You needn't write me another cheque．Just change the date and initial it．你不必给我另开一张支票。你只需改一下日期并签上你姓名的第一个字母。I'm in no...
但是，关于needn't在间接引语中的用法，参见上面第148节C。shan't／won't need to=shan't／won't have to don't／doesn't need to=don't／doesn't hav...
A need既可以作助动词，也可以作普通动词。用为助动词时，它是半情态动词，即它既有情态动词的形式又有普通动词的形式。它的情态动词的形式有need或need not／needn't，可用于各种人称的现在时、将来时和间接引语中。（参见下面C节。）疑问式：need I？等否定疑问式：need I...
Doctor：You needn't go on a diet；but you must eat sensibly and youmustn't overeat．医生：你不必节食，但要饮食有度，不能吃得过饱。Zoo notice：Visitors must not feed the ...
need not可用于现在时和过去时。各人称的形式都一样。（参见第148节。）need not表示无义务”。它表示说话人允许不去做某事，或仅仅表示某事并非必要：Employer：You needn't make two copies．One will do．雇主：你不用打印两份。...
A must表示由说话人加予的义务：Mother：You must wipe your feet when you come in．母亲：你进屋前必须先蹭脚。have to则表示外界的义务：Small boy：I have to wipe my feet every time I come in．小...
A mustmust是情态动词。（参见第107节B。）它用于现在时和将来时。否定式：must not／mustn't疑问式：must I？等否定疑问式：must I not？／mustn't I？等过去时用 had to代替。must与不带to的不定式（即动词原形）连用。它可表示义务...
这个结构用来表示没有覆行义务或不明智地忽略了该做的事。在否定式中这一结构表示从前发生的、错误的或愚蠢的事。You ought to have told him that the paint on that seat was wet．你本应该告诉他椅子上的油漆还没有干。You should have ...
ought／should与进行式连用时表示主语没有履行其义务，做了愚蠢、鲁莽的事等或做事不明智、不慎重等：He ought to be studying for his exam．He shouldn't be spending all his time on the beach．他本该正在...