题目

When Carl ______ at home, he doesn't cook without a parent. ( )A. was B. be C. is D. are 答案：【答案】C【解析】略已知CuSO4溶液分别与Na2CO3、Na2S溶液的反应情况如下：据此判断，下列几种物质溶解度大小的比较中正确的是A.     B.C.      D.