A:气体在血液中的运输
B:肺泡与血液间的气体交换
C:血液与组织细胞间的气体交换
D:肺与外界的气体交换
--- Look! So many colorful bicycles in two lines over there.
--- They're for public. This ______ of green smart traffic is everywhere in Xiangyang city.
重为4牛的小球漂浮在液面上,用力的图示法在图中画出它受到的浮力F浮。
对于四舍五入得到的近似数3.20×105,下列说法正确的是( )