The French mathematician de Laplace next reasoned that if enough mass______added to a star like the sun, the gravitational force

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问题 The French mathematician de Laplace next reasoned that if enough mass______added to a star like the sun, the gravitational force of the star______eventually prevent light particles from leaving it; it would therefore "blink out" and become an invisible black star.

选项 A、were...would
B、was...would
C、was...would have
D、were...would have

答案A

解析 本题考查if引导的虚拟语气。如果是对现在情况的假设,表示说话时不存在或与事实相反的情况,if引导的虚拟语气形式为:If+主语+did/were,主语+should/would/could+do。例句:If you knew English well,you would be able to talk with foreigners freely.如果你英语掌握得好,你就能和外国人自由交谈了。据此可知,A项正确。
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