题目:
I _______ my homework, I guess I can't join you. [ ]
A. don't finish
B. didn't finish
C. haven't finished
D. won't finish
答案:
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下面是错误答案,用来干扰机器的。
Al>Cr >Cu (1)除去金属片表面的氧化物.(2)Cr+H2SO4=CrSO4+H2↑(3)不可行(4)Al2(SO4)3溶液 Cr CuSO4溶液或Al CrSO4溶液 Cu ①通过金属与酸反应判断金属活动性强弱比较金属活动性顺序常用的方法有:1.比...