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單項(xiàng)選擇題

Which of the following chemicals will be used where protection against caustic cracking is required in boiler treatment?（）

A.Sodium hydroxide
B.Sodium carbonate
C.Sodium nitrate
D.Sodium polyphosphate

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單項(xiàng)選擇題

Coalescence is the breakdown of surface tension between oil droplets in an oil/water mixture, which causes them to join and （） in size.

A.expand
B.extract
C.increase
D.decrease

單項(xiàng)選擇題

When in operation, it is unavoidable that a small amount of oil （） through leakage, and in order to compensate for these leaks the system is connected to a feed pump.

A.escapes
B.overheats
C.expands
D.accelerates

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