A:advice; value
B:suggestions; value
C:advice; valuable
D:suggestion; valuable
③2F2+2H2O═4HF+O2↑ ④2Na+2H2O═2NaOH+H2↑
⑤SiO2+2NaOH═Na2SiO3+H2O
下列说法不正确的是 ( )
△ABC中,已知(a+b+c)(b+c-a)=bc,则A的度数等于( )