A:2P+5O2 点燃_ P2O5
B:3Fe+2O2 点燃_ Fe3O4
C:C+O2═CO2
D:H2SO4+NaOH═NaSO4+H2O
(Ⅰ)求C2与C3交点的直角坐标;
(Ⅱ)若C2与C1相交于点A,C3与C1相交于点B,求|AB|的最大值.
北京城区的城市布局呈现出( )
太和镇某小学植树小分队10人参加植树活动.男生每人栽了5棵树,女生每人栽了3棵树,一共栽了42棵树.男生有____人.
It is important ________ people ________ learn team spirit.