Question

—Can we run across the road now?
—No, we _     . We have to wait until the light turns green.

A．needn't

B．mustn't

C．couldn't

D．shouldn't

Answer 1

B

needn't不必； mustn't 禁止，一定不；couldn't不能；shouldn't不应该。句意：我们现在能穿过马路吗？——不，我们一定不要。我们必须等到红灯亮时。情态动词之间最大的区别就是表示语气的不同，结合语境可知选B。