1、我的暑假第十八天： （自然类）(1)Put an ice cube from your fridge into a glass of water. You have a piece of string(线) 10 centimeters long. The problem is to take out that piece of ice with the help of the string. But you must not touch the ice with your fingers.You may ask your friends to try to do that when you
2、are having dinner together. There is a saltcellar on the table. You must use salt when you carry out this experiment.First you put the string across the piece of ice. Then put some salt on the ice. Salt makes ice melt(融化). The ice round the string will begin to melt. But when it melts, it will lose
3、heat. The cold ice cube will make the salt water freeze again.After a minute or two you may raise the piece of string and with it you will raise your piece of ice!This experiment can be very useful to you. If, for example, there is ice near the door of your house, you must use very much salt to melt
4、 all the ice. If you dont put enough salt, the water will freeze again.1. We must use _ when we carry out this experiment. A. fridge B. some foodC. a table D. some salt2. How long will it take to carry out this experiment? A. More than three minutes.B. Five minutes or so.C. Only one minute or two.D.
5、 About ten minutes.3. What is the task of this experiment? A. Put the ice cube into the glass of water with the help of the string.B. Take out the ice cube in the glass of water with the help of the string.C. Take out the ice cube in the glass of water with your fingers.D. Put some salt on the ice c
6、ube and then put the string across it.4. How many things at least are used in this experiment? A. Three. B. Four. C. Six.D. Seven.5. We can learn something about _ from the passage. A. Physics B. biologyC. chemistryD. maths (2)Bamboo is one of the natures most surprising plants. Many people call thi
7、s plant a tree, but it is a kind of grass.Like other kinds of grass, a bamboo plant may be cut very low to the ground, but it will grow back very quickly. A Japanese scientist recorded one bamboo plant that grew almost 1.5 meters in 24 hours! Bamboo grows almost everywhere in the world except Europe
8、. There are more than 1,000 kinds of bamboo that grow around the world on both mountains and plains(平原).Not all bamboo looks the same. Some bamboo plants are very thin. They may only grow to be a few centimeters wide while others may grow to more than 30 centimeters across. This plant also comes in
9、different colors, from yellow to black to green.Many Asian countries have been using bamboo for hundreds of years. They often use bamboo for building new buildings. As a matter of fact, the cables(绳索) that hold up the hanging bridge across the Min River in Sichuan are made of bamboo. The bridge has
10、been in use for more than 1,000 years, and is still holding strong.In Africa, engineers are teaching poor farmers how to find water using bamboo. These African countries need cheap ways to find water because they have no money, and their fields often die from no rain and no water. It seems that bamb
11、oo is one of the best things they can use. Bamboo pipes and drills(钻) can help to make the poor thirsty fields to be watered.1. How is bamboo like grass? A. It is thin and easy to cut.B. It grows everywhere.C. It grows quickly after its cut short.D. It is short and green.2. The sentence “while other
12、s may grow to more than 30 centimeters across.” means “Some other bamboo plants may grow to be very _.” A. short B. strong C. thickD. tall3. From the text we know _. A. most people call bamboo plant treesB. a bamboo plant may grow 4.5 meters in three daysC. the bamboo plant changes its colors when i
13、t growsD. a bridge held by bamboo cable was built thousands of years ago4. Why did the engineers teach the poor farmers in Africa to make use of bamboo? A. Because it is cheap. B. Because it is colorful.C. Because it drills fast.D. Because it is used by Asians.5. Which of the following is NOT true?A. There are many different kinds of bamboo with different colors.B. Cables made of bamboo can last for over a thousand years.C. Bamboo can be used for buildings, bridges and watering projects(工程).D. Bamboo plants are able to grow well in any part of the world.
