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

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

单项选择题 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.