— Do you know Laura’s address?

— _____________. As a matter of fact, I don’t know any Laura, either.

A．I think so

B．I’m afraid not

C．I hope so

D．I’d rather not

下列说法正确的是[ ]

A．增大反应物浓度，活化分子百分数增大，化学反应速率增大

B．难溶物质可能为强电解质，如BaSO₄是强电解质

C．某离子被沉淀完全是指该离子在溶液中的浓度为0

D．K_W随浓度的改变而改变