如图,⊙O是△ABC的外接圆,AB是⊙O的直径,D为⊙O上一点,OD⊥AC,垂足为E,连接BD
病毒这一类生物与其他生物的主要区别是( )
材料二:唐代有人写诗说“太宗皇帝真长策,赚得英雄尽白头”──摘自人教版历史教材
—Well.________ you hadn't wasted so much time playing online games.
—Bill didn't go to school this morning, did he?
—_______. Though he was not feeling very well.