As the propeller turns，voids are formed on the trailing and leading edges of the propeller blades causing a loss of propulsive efficiency，pitting of the blades，and vibration. These voids are known as（）.

As oil pipe line connections were broken，（）quantity of ...

单项选择题As oil pipe line connections were broken，（）quantity of oil was caused to spill onto the wharf and into the dock water.

Anchors are prevented from running out when secured by ...

单项选择题Anchors are prevented from running out when secured by the（）.

An LWT anchor often has difficulty tripping in（）.A.sand...

单项选择题An LWT anchor often has difficulty tripping in（）.