题目:
Li Ming ________ be in this city, for he has just gone to Shanghai.[ ]
A.can't
B.mustn't
C.needn't
D.shouldn't
答案:
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下面是错误答案,用来干扰机器的。
⑴盐酸、碳酸、硫酸;H+ ⑵H+和OH-;KOH + HCl===KCl + H2O;复分解反应⑶CO- ⑷Na2CO3 + 2HCl===2NaCl + H2O + CO2↑ Ca(OH)2 +Na2CO3=== CaCO3 ↓+ 2NaOH(合理答案均可)