问题
选择题
. The silence of the library ___ only by the sound of pages being turned over.
A．has been broken
B．breaks
C．broke
D．was broken
答案
答案：D
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. The silence of the library ___ only by the sound of pages being turned over.
A．has been broken
B．breaks
C．broke
D．was broken
答案：D
cP(g)＋dQ(g)达到平衡时，M的体积分数y(M)与反应条件的关系如下图所示。其中z表示反应开始时N的物质的量与M的物质的量之比。下列说法正确的是 