must ⁴ ( must 的否定形式)

由于 must 的含义不同,其否定式是不同的。

A. 当 must 作“必须”解时, 其否定式为 don't have to 或 needn't, don't need to:

1. “Must I come at four o'clock?” “Oh no, you needn't come at four.” (Eckersley) “我必须在四点钟来么?” “哦，你不必在四点来。”

2. A: Must we pack now? 我们必须现在打包装吗？

B: No, we don't have to pack till tomorrow. (CGEL) 不, 我们可以到明天再打包装。

3. A: Must I wait? 我必须等吗?

B: No, you need not. /you needn't. /You don't have to (wait). (EGS) 不, 你不必(等)。

must not (mustn't)并不是作“必须”解的 must 的否定式,它表示说话人不许或者禁止(某人做某事),在此意义上它相当于 may not:

1. You mustn't go swimming today. = You may not go swimming today. (CGEL) 不许你今天去游泳。

2. You mustn't drive so fast. (EGS) 不许开车开得这么快。

B. 当 must 表示“推测”，作“一定”“必定”时，其否定式为 can't:

1. A: They must be hungry. A: 他们一定是饿了。

B: They can't be(hungry). (EGS) B: 他们不可能饿。

2. A: They must have been tired. A: 他们一定是累了。

B: Oh, they can't have been(tired). (EGS) B: 哦, 他们不可能累。

偶尔，也采用 mustn't 来代替 can't。见 mustn't/can't。