装炮班的主要作业内容有哪些？
参考答案：射孔器搬运作业、射孔器组装作业、吊装作业、射孔器发放和接收作业。
His _____ to become a pilot was held back by his poor eyesight. [ ]
A. destination
B. inspiration
C. ambition
D. promotion
亚病毒指如下哪种病原体( )
A．RNA病毒B．DNA病毒C．包膜病毒D．类病毒E．衣原体
