A:Mg+O2 点燃__ MgO2
B:4Fe+3O2 点燃__ 2Fe2O3
C:C+O2 点燃__ CO2↑
D:2HgO △__ 2Hg+O2↑
棱台不具备的性质是( )
A. B.
C. D.
在四棱锥P-ABCD中,AB→=4,-2,3,AD→=-4,1,0,AP→=-6,2,-8,则这个四棱锥的高h=( )
Jenny learns Chinese many ways,such as watching Chinese movies and reading Chinese newspapers.