Look! They all _____ a ball in their hands. [ ]
A. are having
B. having
C. has
D. have
答案:D
施工机械设备上必须配备齐全有效的安全装置,包括()。
A.防护设施
B.监测装置
C.警示装置
D.报警装置
E.保险限位装置