A:2Na +2H2O =2NaOH +H2↑
B:Cl2 +H2O =HCl + HClO
C:2F2 +2H2O =4HF +O2
D:CaO +H2O =Ca(OH)2
____
— your father?
—He's a teacher.
下列结论不正确的是( )
如图,AB为⊙O的弦,⊙O的半径为5,OC⊥AB于点D,交⊙O于点C,且CD=1,则弦AB的长是____.