将中国古代政治制度“①三省六部制②行省制③郡县制”按产生先后次序排列,正确的是[ ]
A.①②③
B.③①②
C.③②①
D.②①③
答案:B
群落之间、群落与环境之间相互关系的可见标志是( )
A.群落外貌 B.群落水平结构C.群落垂直结构 D.生态位
One of my close friends made great progress in her studies so her teachers ___ her, and I _____ her.
A.were happy with; was happy with
B.were happy for; was happy for
C.were happy with; was happy for
D.were happy for; was happy with