There are ( ) and crayons on the floor.
A:rulers
B:books
C:pencils
A.(如水绵)CO2+2H2O CH2O+O2+H2O
B.(如:红硫细菌)CO2+2H2S CH2O+2S+H2O
C.(如:硝化细菌)2NH3+3O2 2HNO2+2H2O+66kj
2NHO2+O2 2HNO3+180kj
nCO2+2nH2O+841kj CH2On+nO2+nH2O.
函数f(x)=ax-logax(a>0,a≠1)的零点个数 ( )
已知集合A={x|x2+4x+3≥0},B={x|2x<1},则A∩B=( )