单项选择题 The auxiliary steering gear must be capable of being brought speedily into operation and be able to put the rudder over from 15 degrees on one side to 15 degrees on the other side in no more than （） with the ship at its deepest service draught and running ahead at the greater of one half of the maximum service speed or （）.

单项选择题 The main steering gear must be able to steer the ship at maximum ahead service speed and be capable at this speed, and at the ships deepest service draught, of putting the rudder from 35 degrees on one side to 30 degrees on the other side within no （）.

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