题目

What kinds of homes will we live in the future? Nobody ______ be sure, but scientists are working out new ideas now.         A. will            B. may            C. can           D. must 答案：C下列物质间的转化不能一步完成的是 A. CaCO3→CaO       B. CO2→CO      C. H2SO4→H2O     D. Cu→Cu(OH)2