2NaOH+SO₂═Na₂SO₃+H₂O …（a）

Na₂SO₃+H₂O+SO₂═2NaHSO₃…（b）

2NaHSO₃ $\underset{\_}{\underset{\_}{\Delta }}$ Na₂S₂O₅+H₂O …（c）

实验装置如图：

Dear Jenny,

    Now we are in the hospital of our city . My mother and I have a bad cold . We sees many children here . Some people have a cold. Some people have a headache. Some people have a fever. They a re waiting outside the doctor's room .Now it's our turn.

Yours,

Jack

下列关于水的认识正确的是（    ）