人体呼出的二氧化碳是在哪产生的?( )
A:肺泡
B:静脉血
C:气管
D:细胞
八哥与蝉对话①
鸲鹆②之鸟,出于南方,南人罗③而调④其舌,久之,能效人言,但能效数声而止;终日所言,唯数句而已。蝉鸣于树,鸟闻而笑之。蝉谓之曰子能人言甚善然子之所言犹若未言也。曷若⑤我自鸣其意哉?鸟俯首而惭,终身不复效人言。
【注】①本文据《叔苴子》改编。②鸲鹆(qú yù):即八哥。③罗:张网捕捉。④调:调教。⑤曷若:怎么像。
Mr. Chen is very _________ every day. He has no time to help his daughter with her homework.