B

I am going to tell you an unbelievable story. This afternoon a __41___(poor)  dressed gentleman came into my restaurant. Nobody knew who he was and __42___he came from. After __43___(sit) down, he ordered a lot of food. He stared at it and then _44___ (eat) it up very quickly.

To be_45___, we doubted whether the man was able to pay for the food. When he was asked to pay the bill, the gentleman asked if we would mind__46__ (wait) just a few minutes. Then we were _47___ (shock) to see that he took a million pound bank note. __48__(fortunate), we could not change the bank note as it was too large. So I gave this strange but very rich man a _49__ dinner, in the hope__50__he might come to our restaurant again.

下列物质加入水中，使水的电离程度增大，且所得溶液显酸性的是（）

A.CH₃COOH

B.Al₂（SO₄）₃

C.NaOH

D.Na₂CO₃