— What did the head teacher say at the meeting?

— He said, "We _____ be proud of working hard. We mustn't be lazy." [ ]

A. must

B. needn't

C. may

D. can't

电控汽油喷射系统的燃油供给子系统中一般有油箱、油泵、滤清器、喷油器、（）、管路等主要部件。