Lin Tao can't be at home. I saw him _______ here a few minutes ago. [ ]

A. plays

B. to play

C. playing

D. played

现有以下七种微粒：①H ②H⁺ ③O ④H₂ ⑤O₂ ⑥OH^-⑦H₂O，请将符合要求的微粒的序号填在横线上：

(1)电解水得到的产物是_______________。

(2)能使无色酚酞溶液变红色的微粒是_____________。

(3)不含电子的微粒是__________。

(4)所含电子数相同的微粒是_____________。