问题 应用设计题

今有一种未知液体和一小块未知固体,将液体倒入水中,发现液体沉入水底,将固体放入水中,也沉入水底.请你设计一个比较这种液体和小块固体密度大小的方案,器材不限,简要说明方法即可.

答案

方案一:用天平、量筒、烧杯、水、细线,测量液体和小块固体的密度进行比较.

方案二:把固体放入这种液体中,若固体下沉,则固体的密度大于液体的密度;如固体悬浮在液体中,则固体的密度等于液体的密度;若固体漂浮在液体中,则固体的密度小于液体的密度.

多项选择题
阅读理解

阅读理解

     Sitting in the play area of the doctor's office, my children, Paul, four, and Bailey, three, built a Lego

tower while we waited to be called for Paul's examination.

     "Good job, you guys, "I said, trying not to sound too tired.My husband was away on business, and

it was difficult being alone with the kids.At times I felt like I was living in the jungle (丛林) rather than

the suburbs.

     "Don't put the Lego in your mouth, Bailey, " I said.Paul grabbed (抓取) it from him."That's not nice,

Paul, " I said.He gave back the Lego.I looked around the waiting room.A woman was eating something,

a couple were talking, and an old gentleman in a blue jacket was reading a magazine.I wished I could sit

quietly for a while.I wanted to be able to take a rest, or go shopping alone.At once, I was ashamed of

myself.What kind of mother was I?"God, " I thought, "help me to be the very best mom I can be."

     The nurse came into the waiting room to get us.Just at that moment, the old gentleman in the waiting

room put down his magazine and came up to me.With a smile on his face, he said, "Your children are

most certainly lucky to have such a wonderful mother.""Thank you, "I replied in a low voice and watched

him walk back to his seat.We followed the nurse into the examination room.While she weighed Paul, I

told her how that man had made my day.

     Motherhood is still a jungle sometimes, but now when I feel tired I remember the encouraging words

of the old gentleman.

1. The writer went to the doctor's office because________.

A. one of her children liked to play there

B. her son Paul needed an examination

C. she was tired and needed to see her doctor

D. she wanted to have all her children examined

2. From Paragraph 2, we know the writer felt that looking after her children alone was________.

A. unfair B. happy  

C. hard  D. interesting

3. The writer criticized Paul when he________.

A. put the Lego into Bailey's mouth

B. took away the toy from Bailey

C. made trouble in the waiting room

D. didn't follow her advice

4. In the old gentleman's opinion, the writer________.

A. lived a very hard life

B. was a very good mother

C. didn't love her children enough

D. was lucky to have so lovely children

5. What can we learn from the passage?

A. The writer often went shopping alone.

B. The writer's husband was always on business.

C. The writer doesn't know how to be a good mother.

D. The writer was greatly encouraged by the old gentleman's words.