并且，由于它们是在地下形成的，而不是由地表水流形成，所以并不是所有的通道都有通向外部世界的开口。
And, since they were created underground and not from flowing surface water, not all these passageways have an opening to the outside world.
由于地铁行人交叉路的设计得到了改善，乘客在地下换乘会更便捷。
Passengers will also be better able to transfer between underground lines as the design of underground pedestrian crossings has been improved.
文章首句指出：“由于‘地震反射法’(sr)在勾划地球的地下层面这方面的准确性，该方法一直是探寻石油储备的最重要的工具。” 这是一个判断句，为结论。
Because of its accuracy in outlining the Earth's subsurface, the seismic-reflection method remains the most important tool in the search for petroleum reserves.
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