⑴before ____ A. high
⑵bad ____ B. never
⑶low ____ C. good
⑷always ____ D. catch
⑸throw ____ E. after
设向量a→=(1,2),b→=(x,1),当向量a→+2b→与2a→-b→平行时,则a→·b→等于 ( )
2C+O2 点燃__ 2COC+O2 点燃__ CO2 2CO+O2 点燃__ 2CO2