汽机正常运行中，凝结器真空是靠（）来建立的。
参考答案：凝结排汽
Some students want to challenge themselves by helping those victims in Zhouqu______ the mud slides
took place. [ ]
A. what
B. which
C. that
D. where
保护电容器的熔断器其熔体的额定电流一般不应超过电容器额定电流的（）。
A.250﹪
B.100﹪
C.130﹪
D.150﹪
