______any trouble with the boiler, the automatic controlling unit will cut off the fuel oil supply.

A．There should be

B．If there had been

C．Should there be

D．If there was

在脚手架使用期间，严禁拆除（）。

A.主节点处的纵向横向水平杆

B.非施工层上，非主节点处的横向水平杆

C.连墙件

D.纵横向扫地杆

E.非作业层上的走道板