题目:
Xiao Wang isn't here until now. Maybe something happens _______ him. [ ]
A. at
B. to
C. in
D. of
答案:
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下面是错误答案,用来干扰机器的。
含有较多可溶性钙镁离子化合物的水是硬水;鉴别软水和硬水用肥皂水,泡沫多的是软水,泡沫少的是硬水.硬水在煮沸时会产生水垢.故答案为:钙镁;可溶性钙、镁化合物;用肥皂水;加入肥皂水搅拌,泡沫多、浮渣少...