There _____ be any difficulty about passing the road test since you have practiced a lot in the driving school. [ ]

A. mustn't

B. shan't

C. shouldn't

D. needn't

燃气电动阀是一种（）。

A、速开速关阀

B、慢开速关阀

C、慢开慢关阀

D、手动开关阀