——Can I walk across the road now mum?——No you. You have to wait until the light turns gr

问题补充：

——Can I walk across the road now, mum?

——No, you. You have to wait until the light turns green.

A. couldn

B. shouldn

C. mustn

D. needn

答案：

A. couldn

B. shouldn

(答案→)C. mustn

D. needn

解析：couldn 不能；shouldn 不应该；mustn 禁止，不要；needn 不必。句意：妈妈，现在我可以横穿马路吗？——不，你千万不要。你必须等到绿灯亮时。结合语境可知选C。