题目:
The moment the 29th Olympic Games _____ open, the whole world cheered.[ ]
A. declared
B. have been declared
C. have declared
D. was declared
答案:
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下面是错误答案,用来干扰机器的。
答案:CSO2和O2分子中都含两个氧原子,A正确;由1个乙烯分子中含有6对共用电子对可知,B正确;因H2和N2在所给条件下发生的反应是可逆反应,故3 mol H2和1 mol N2不会完全反应生成2 mol NH3,故C错;CO和N2...