单项选择题
A tow can override its tug as a result of（）.
A.a mechanical breakdown on the tug B.adverse tidal current conditions C.the tug reducing its speed D.All of the above
单项选择题 A time diagram is a diagram on the plane of the（）.
单项选择题 A time diagram is a diagram of the celestial sphere as observed from above the（）.
单项选择题 A thrust block is designed to（）.
