当钻井液柱压力一定时，不同的情况井底压力是不变的。
参考答案：错
解析：井底压力随工况不同而不同。
中碳钢碳的质量分数范围是（）。
A.0.0218%~2.11%
B.0.0218%~0.77%
C.0.20%~0.60%
D.0.60%~0.80%
In the past few years, so many areas throughout the world have been hit by such destructive earthquakes, snowstorms and tsunamis ________ we have never experienced before, ________ makes us worried a lot about nature disasters.
A．that; that
B．as; which
C．which; it
D．when; as
