单选题
How is crude oil brought to the surface?
A、
By expansion of the hydrocarbons.
B、
By pressure and pumping.
C、
By vacuum created in the drilling pipe.
D、
By expansion and contraction of the earth's surface.
【正确答案】
B
【答案解析】
[解析]由第一段末句“Pressure at the source or pumping forces crude oil to the surface．”知B为正确答案。
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