A:①和②的成分完全相同
B:A是氧气,B是二氧化碳
C:据图判断此血管为小动脉
D:组织细胞中B浓度低于②
Hangzhou is __________ to hundreds of foreign friends who are working and studying here.
塔里木盆地绿洲的水源主要来自( )