根据天然气管输的需要和要求，增压站可以设在天然气净化厂或输气干线首站之前，也可设在输气干线中。

To safely anchor a vessel there must be sufficient scope in the anchor cable. Scope is the ratio of（）.

A.weight of cable to weight of vessel

B.weight of cable to weight of anchor

C.length of anchor to depth of water

D.length of cable to depth of water