题目列表(包括答案和解析)
| |||||
Three kids have been learning chemistry for only a few months. But they have already begun to challenge (挑战) a world famous scientist!
Li Weichi, Huang Runling, and Xiao Yan are from Zhongshan Huaqiao Middle School in Guangdong. They have just found a red cabbage that could be a new kind of acid-base indicator (酸碱指示剂). They want it to take the place of litmus (石蕊) paper.
"We've learnt to think of and ask questions about life by ourselves," said Li, "We work well with each other."
British scientist Robert Boyle discovered the use of litmus paper over 300 years ago. Now it is used widely in experiments all over the world.
But when the kids did some experiments in class last
winter, they saw that the litmus paper didn’t turn very blue with base matter.
It'
s
hard to get a clear result.
Will there be a better indicator than litmus paper? The three kids decided to try and find out!
How? They went to collect over 40 plants in parks, gardens and markets. Then they ground (研磨) leaves, flowers and stems (茎) to get the pigments (色素) from them.
The kids mixed pigments with acid and base. They spent months watching carefully to see which paper showed the best colour change. They decided it was the litmus paper!
"It's our first scientific journey, Huang said, "But it makes me want to try harder."
1. Whom did the three kids want to challenge?
A. Their chemistry teacher. B. Their headmaster.
C. Robert Boyle D. Thomas Edison
2. From the text, a red cabbage is a kind of ____.
A. plant B. animal C. paper D. liquid
3.What is widely used as the acid-base indicator now?
A. red cabbage B. litmus paper
C. any plant D. any flower
4.The story mainly tells us ____.
A. how to make litmus paper B. about the three kids' spirit
C. scientists were wrong D. the kids are heroes
|
Dear Mom, I’m sorry that I can’t go back home for Mother’s Day next week. On that day, I’ll have to go to an important meeting for my boss, who helps me a lot with my work and life here. But I’ll find time to see you at home soon. Mom, thank you for everything you’ve done for Tim and me. After Dad died ten years ago, you had to work in a supermarket in the daytime and in a restaurant at night. But you always gave us two your love and care. Though you don’t have to work now, I still remember your coming home and feeling tired many evenings. Tim is going to finish his studies next month. He said he would move back from school and look for a job neat home. I’m glad you won’t live by yourself anymore. Let’s plan to take a trip in the near future. It’s been years since the three of us took a trip together. Happy Mother’s Day. I love you, Mom. Best wishes, John
1.What can we learn about John’s mother? (A) She lives by herself now. (B) She still works day and night. (C) She will make a plan to save money. (D) She used to be too busy to care for her children.
2.What do we know from the letter? (A) John has two brothers. (B) John is unhappy with his boss. (C) John has to work on Mother’s Day. (D) Tim will leave home for his job soon.
3.Which is said in the letter? (A) John’s father died at work. (B) Tim will look for a teaching job. (C) John bought a gift for his mother. (D) John hopes to take a trip with his family. |
| |||||
Salesman: $73.07,please.
Peter: What? Show me the receipt.
Salesman: Here it is.![]()
Peter:Look. The price on this shirt is $17. But the receipt says $27.
Salesman: You are right. The receipt is wrong.
Peter: And what is the $5.57 for?
Salesman: That’s for tax(税).
【小题1】The $5.57 is for the ___________.
| A.tax | B.bags | C.jacket | D.shirt |
| A.On June 17. | B.At noon. |
| C.On June 25. | D.In the morning |
湖北省互联网违法和不良信息举报平台 | 网上有害信息举报专区 | 电信诈骗举报专区 | 涉历史虚无主义有害信息举报专区 | 涉企侵权举报专区
违法和不良信息举报电话:027-86699610 举报邮箱:58377363@163.com