— Mum, can you give me some advice on how to behave myself at the table?
— Well, I do have some advice. , please keep quiet while eating.
A:In all
B:Of all
C:At all
D:Above all
平面直角坐标系中,△ABC的三个顶点坐标分别为A(0,4),B(2,4),C(3,﹣1).
化学键
H﹣H
O=O
H﹣O
键能(KJ/mol)
436
496
463
对于反应:2H2(g)+O2(g)=2H2O(g)△H=a KJ/mol,a的值为( )