The various pumps and lines are _____ to some extent so that each pump can act as an alter

The ship’s generator broke down, and the pumps had

Before liquid can flow into a pump, the air in the suction line must be _____ sufficiently

Pumps and fine filters are arranged _____ with one as standby.A.in duplicateB.in doubleC.a

Many people are struggling at the ______ line, short of food and shelter.A、povertyB、po

There are various ways of solving the prob

Various forms of lighting and special effects are the indispensable elements of modern