It’s beyond our comprehension that Jim, who tops the class in English, ________ have difficulty translating such a simple sentence.

A．shall

B．should

C．might

D．must

检测隧道式冷丝机网面风速均匀度时，可用风速表测试距振动式输送机网面（）mm处各点的风速分布，平均误差应不大于±2%。