题目

Passengers ________ talk to the driver while the bus is moving, because it will take his focus off the road. 答案：mustn't 句意：当公共汽车开动时，乘客不得与司机交谈，因为这将把他的注意力从路上转移开来。此处表示“禁止，不允许”，故用mustn't。方程的解是 [     ]A.2 B.0 C.1 D.3