单项选择题 What is the purpose of the intermediate spring?（）

单项选择题 What could cause a significant difference between actual chain tension and the tension measured by the tensiometer? （）

单项选择题 We took usual steps:sounding the depth，reversing and stopping engine，paying out anchor and 60 fathoms of chain cable in the depth of 12 fathoms．The operation above is（）.