问题
单项选择题
______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
答案
参考答案：C
解析： 30．此句为倒装形式的虚拟条件句，相当于If there should be any trouble with the boiler, 与 将来可能情况相反。
