People did not begin to use unmanned vehicles in undersea exploration until recently becau

外语类 2018-01-17 03:11:21 专四已帮助人

People did not begin to use unmanned vehicles in undersea exploration until recently because of______.

A．the communication problem

B．the movement of waves

C．the ocean depths

D．the problem of vacuum

请帮忙给出正确答案和分析，谢谢！

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正确答案：A
就为什么“人们直到最近才开始在海底探索中使用无人驾驶的遥控装置”这一问题，作者在第四段开头和第五段开头明确地给出了原因：“onereasonforthisiscommunicatingwithvehiclesinorbitismucheasierthantalkingtothoseunderwater”及“Forasimilarreason,knowingwhereyouareunderseaismuchmoredifficultthaninspace”。因此可以断定[A]是正确答案。