The population of many Alaskan cities has ______ doubled in the past three years.

A．as great as

B．as many as

C． more than

D．larger than

关于弹性驱动油藏下列说法中正确的是（）。

A、弹性驱动油藏有原生气顶

B、弹性驱动油藏在开采过程中，油藏压力始终低于饱和压力

C、弹性驱动油藏地层压力随开采时间增加而下降

D、弹性驱动油藏生产汽油比随开采时间增加而下降