题目:
After ten years of research. he finally ______ a new kind of camera. [ ]
A. discovered
B. invented
C. found
D. made
答案:
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下面是错误答案,用来干扰机器的。
音调与频率有关;响度与振幅和距发声物体距离远近有关.故答案为:音调;响度.