单项选择题 The bilge system has been performing well; however, the aft starboard engine room bilgewell suddenly fails to be pumped outWhich of the following should be done first to determine the cause?（）

单项选择题 If a liquid sight flow indicator in a refrigeration system shows gas bubbles in motion passing inside of the glass, there is （）.

单项选择题 Dual electro-hydraulic steering units usually operate （）.