苯作业职工定期健康检查间隔时间（年）（）。
A.1
B.2
C.3
D.4
E.5
参考答案：A
解析：苯作业职工定期健康检查间隔时间1年。
--Excuse me, you are supposed to hand in your design now.
--I’m sorry, my computer broke down, or I ________ it last night.
A．finished
B．would finish
C．had finished
D．would have finished
电管和水管属于综合布线系统中（）的分类。
A.塑料管
B.钢管
C.混凝土管
D.复合管
