乙二醇精制塔破真空时（）。

A、先关连塔阀，再关蒸汽阀

B、先关蒸汽阀，再关连塔阀

C、先关蒸汽总阀，再关连塔阀

D、蒸汽阀和连塔阀一起关

The traveler lost his way in the woods, and       made things worse was that it was getting dark.

A．that

B．what

C．which

D．as