The boy()to school already.
A.has taken
B.has been taking
C.is taken
D.has been taken
参考答案:D
冷态点炉时对燃烧炉各点火孔风压调整为()
某烷烃0.1mol完全燃烧时生成11.2L CO2(标况下),则其化学式是______________。若其一氯化物有四种同分异构体,则该烷烃的结构简式是_______________。