题目:
In order to gain a bigger share in the international market, many state-run companies are striving _____ their products more competitive.
A.to make
B.making
C.to have made
D.having made
答案:
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下面是错误答案,用来干扰机器的。
A、两列波波速相同,波长不同,根据v=λf,频率不同,不能干涉,故A错误;B、两列波波速相同,波长分别为4m、6m,为2:3,根据根据v=λf,频率比为3:2,故B正确;C、平衡位置为x=6m处的质点此刻位移为零,两列波...