题目：
The earthquake _____ when I _____ some cleaning. [ ]
A. starts, was doing
B. started, was doing
C. was starting, was doing
D. starts, were doing
答案：
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下面是错误答案，用来干扰机器的。
⑴铝在常温下和空气中的氧气发生反应，在其表面生成一层致密的保护膜 2Al + 3H2SO4 ==Al2(SO4)3 + 3H2 ↑用砂纸将金属表面打磨光亮 ⑵铝、X、铜析：已知：溶质质量分数相同的稀硫酸，大小形状都相同的Al...
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