网址：http://m.1010jiajiao.com/timu3_id_2750313[举报]
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
查看习题详情和答案>>
根据中问提示，完成下面对话，每空一词。
汤姆和李明在北京机场下了飞机，几分钟后就可到达北京饭店。他们正朝对面出口处走去，此时汤姆想吸烟。李明告诉他严禁吸烟，汤姆只好等到出了机场再吸。
Tom：We’ve arrived at Beijing 1 , haven’t we?
Li Ming：Yes．We can 2 Beijing Hotel 3 a few minutes．
Tom：But where’s the 4 ?
Li Ming：It’s just 5 to us, about three hundred metres 6 with a sign “EXIT” above．
Tom： 7 beautiful the airport is!By the way, can I smoke here?
Li Ming：I’m sorry．Look at the sign “No 8 ”．
Tom：OK, I won’t smoke 9 we go out 10 the airport．
Li Ming：There’s the exit(出口)．Let’s go．
Most American families are smaller than the families in other countries. Most American families have one or two parents and one or two children each.
Children in the US will leave their parents’ home when they grow up. They usually live far from their parents because they want to find good jobs. They often write to their parents or telephone them. And they often go to visit their parents on holiday.
Parents usually let their children choose their own jobs. Americans think it important for young people to decide on their lives by themselves.
Children are asked to do some work around their house. And in many families, children are paid for doing some housework so that they learn how to make money for their own use.
1.The size of most American families is _________that of other countries
A. larger than B. smaller than C. as big as D. as small
2.When children grow up, they leave their parents’ home to_________.
A. get married B. be free C. find good jobs D. study
3.They visit their parents__________.
A. on weekdays B. on weekends C. at any time D. on holiday
4.Which of the following statements is WRONG?
A. Children have the freedom to choose their own job.
B. Parents don’t ask their children to do the housework.
C. Parents think it important for children to make their own decision.
D. When children grow up, they usually live far away from their home.
5.Some parents pay their children for doing housework because ___________.
A. children can learn how to make money for themselves
B. their children required them to do so
C. they are rich
D. it is required by law
查看习题详情和答案>>
根据短文内容及首字母提示完成单词
Coffee has been a part of people's lives for t 1 of years, and it is still a favorite d 2 in the world, Here is a story of coffee about h 3 it was discovered.
The story tells us coffee was discovered in Africa long long a 4 . One day a farmer was w 5 his goats, and saw them e 6 some berries (浆果) from a plant. The goats became very active a 7 they ate the berries. The man often felt tired, so he decided to try the berries, t 8 . T 9 his surprise, he didn't feel tired any more. Coffee plants were thus discovered. The coffee was t 10 from Africa to other countries in Europe. After that the farmers started to grow coffee plants there, especially in South America.
查看习题详情和答案>>阅读理解。
There are many colours in nature．But do you know if a colour has weight?I think you'll say“no”．But I am afraid you are wrong．If you don't believe, you may do a small experiment．
First, put two objects with the same weight into two boxes．Then cover the box．Third, wrap(包)one box with a red piece of paper, the other with a white piece of paper．OK．Now hold the boxes before your hand one by one．It is certain that you will think the red one is a little heavier．
Why do you think so?A scientist found that colours, different, different, have, in, man's, mind, weight．① So he did many tests and at last he got the result．That is to say, every colour has its own weight in our mind and their order is the same．The h ________ ② colour is red, then blue, green, orange, yellow and white．
A scientist told us that colours also have s ________ ③．Can you smell the colour?Of course not．Then why did the scientist say so?That is because every colour stands for(代表)a kind of light with a certain wave-length(波长)．It reaches our brain through sense organs(感觉器官)．
According to this discovery, scientists say that people accept(接受)the colours they like, and refuse the colours they hate．So your body and mind will be h ________ ④ by using the colours you like．Or you'll be nervous or get ill．For example, if you stay in a room with red windows, wallpapers and furniture for two hours, you'll feel you have been there for four hours．But if the room is blue, you'll feel you have been there for only one hour．Another example, if a person walks out of a red room and into a blue room, his temperature will fall．That means our body temperature will change with different colours⑤．
根据短文内容：
1．将画线部分①连成宾语从句：________________
2．完成短文中所缺的单词：②h ________; ③s ________; ④h ________
3．将画线部分⑤译成汉语：________________
4．判断下列各句正(T)误(F)。
□Stay in a room with red wallpapers and furniture, and you'll feel the time is slow．
□If a person walks out of a blue room and into a red room his temperature will fall．
□Not all colours stand for a kind of light with a certain wave-length．