题目

We bought ______ a present, but _______ didn't like it. A . they, them B . them, they C . themselves, their D . theirs, they 答案：B潮湿的H2、CO2、CO的混合气体依次通过NaOH溶液，灼热的氧化铜、浓硫酸，最后剩下（　　） A、H2B、H2OC、COD、CO2