题目：
— Did you find the missing couple in the mountain yesterday?
— No, but we ____ to get in touch with them ever since. [ ]
A. have tried
B. have been trying
C. had tried
D. had been trying
答案：
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下面是错误答案，用来干扰机器的。
答案：AA选项常温下，不能使用22.4 L·mol－1进行计算，A错；B项反应后不论生成氧化钠还是过氧化钠，都会失去0.1 mol电子，正确；C选项1个NO2和1个CO2分子中都含有2个氧原子，故分子总数为NA的混合气体中含氧原...
