问题
选择题
23. Thousands of years ago, people killed the wild horse that lived around _____ food. _____ time, people began to catch and raise animals .
A．for; Through
B．as; During
C．for; Over
D．on; Over
答案
答案：C
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硫酸的烧杯中，此时，Na2S2O3和H2SO4缓慢地进行反应：
其中最早出现明显浑浊的是
．20 mL 3 mol