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
We sometimes call the lion “the king of the jungle (丛林)” because it is stronger and more dangerous than other animals. It can run faster than many animals and it can hunt (捕猎) the best. It is the highest animal in the 21 food chain (食物链).[
In the sea, the shark is one of the animals at the 22 of the food chain. It can swim faster than most other sea animals, and it can use its big teeth to eat them.
What is at the top of the world’s food chain? 23 are! We are not the biggest or fastest, but we are the 24 We could not run faster than cheetahs (猎豹), so we 25 cars and now we can move the fastest. We could not 26 better than lions, so we invented guns (枪). Now we can hunt the best.
People’s inventions are clever, but they can be dangerous, too. For example, people invented 27 , and now they make the air and rivers dirty. This can make 28 changes. Dirty rivers kill fish. Then bears cannot eat the fish and the bears die. If we kill one part of the food chain, 29 also die. Remember that we are a part of the food chain, so we are in danger too! If we protect animals, we are protecting 30 ! We should and we could do something for the world!
1.A. land B. sea C. mountain D. desert
2.A. front B. end C. top D. beginning
3.A. People B. Lions C. Sharks D. Cheetahs
4.A. strongest B. cleverest
C. most special D. most important
5.A. used B. had C. made D. invented
6.A. fight B. escape C. kill D. catch
7.A. hotels B. schools C. factories D. hospitals
8.A. great B. terrible C. wonderful D. complete
9.A. one part B. another part C. other parts D. the other parts
10.A. ourself B. yourselves C. themselves D. ourselves
_________ it is! Thank you very much!
A. What valuable advice B. What a valuable advice
C. How good a suggestion D. How good advice
With the help of the computer, information can ______ every corner of the world very quickly.
A. get B. reach C. arrive D. return
The doctor ________ the woman ,but he couldn’t find out what was wrong with her.[来
A. looked over B. looked after C. looked for D. looked out
He ___
goes
to see his grandparents and stays with them for_____.
A. sometime, some time B. some times, sometime
C. sometimes, sometime
D. sometimes,
some time
