根据短文内容, 用方框所给单词的适当形式填空，每词限用一次。

about,  sleep,  quick,  much,  why

"Dreams may be more important than sleep. We all need to dream," some scientists say.

Dreams take up about one quarter of our 小题1:._________ time. People have several dreams each night. Dreams are like short films. They are usually in colors. Some dreams are like old films. They come to us over and over again. That may be because the dreamer is worrying about something. Dreaming may be a way of trying to find an answer.

Some people get new ideas 小题2:._________ their work from dreams. They may have been thinking about their work all day. These thoughts can carry over into dreams.

Sometimes we wake up with a good feeling from a dream. But often we can't remember the dream. Dreams can disappear (消失) 小题3:.________ from memory.

Too much dreaming can be harmful. The 小题4:. _________ we sleep, the longer we dream. The mind is hard at work when we dream. That is 小题5:. ________ we may have a long sleep and still wake up tired. 

已知常温下某水溶液中由水电离出来的c(H⁺)=10^-14mol/L，溶液中可能含有①Fe²⁺ ②Cl^- ③HCO₃^- ④Na⁺ ⑤NO₃^-⑥Al³⁺ 将上述离子任意两种组合，肯定能在该溶液中大量共存的是[ ]

A. ②④

B. ①⑤

C. ④⑤

D. ③④