题干
Many children, _____ parents are way working in big cities, are taken good care of in the villages.
A：their
B：who
C：whose
D：with whom
答案(点此获取答案解析）
C
Many children, _____ parents are way working in big cities, are taken good care of in the villages.
A：their
B：who
C：whose
D：with whom
N2O4，所得混合气体中NO2的体积百分含量为40%，此时，混合气体的平均分子量为
