Do you have to buy this hat?No,I________.It isn't necessary.(a)mustn't (b)won't (c)needn't (d)don't need选择哪一个,为什么?

Do you have to buy this hat?No,I________.It isn't necessary.(a)mustn't (b)won't (c)needn't (d)don't need选择哪一个,为什么?
Do you have to buy this hat?No,I________.It isn't necessary.
(a)mustn't (b)won't (c)needn't (d)don't need
选择哪一个,为什么?

Do you have to buy this hat?No,I________.It isn't necessary.(a)mustn't (b)won't (c)needn't (d)don't need选择哪一个,为什么?
选 C .
needn't 表示“不需要”.这里“need”用作情态动词（就是 must should can could 这类动词）.
而 D 中的 need 是行为动词（或称实意动词,就是 go come play hold speak 这一类动词）.
此题中的“需要”其实是指“需要买”而不是“需要这顶帽子”（实际上可以不分这么清楚,但是为了便于理解和区分,你可以这么理解）.
你只要记住：“需要买”就用情态形式,“需要这顶帽子”就用实意形式.