题目内容
It may seem easy to say that plants and animals are different. Any child can tell the difference between a tree and a dog. But those differences are far deeper then just what they look like. The cells (细胞) that plants are made up of are different. In other words, the cell wall of plants has something special.
First of all, it’s important to find that not all plant cells have a cell wall. Besides, there are many differences of a cell wall based on the kinds of plant. The following is meant to be what a plant cell wall is like.
The cell wall of a plant is on the our side of the cell membrane (膜). It is usually hard and cannot be bent easily, but the degree of flexibility (韧性) of the cell wall is different. It is based on the special use that the cell has in keeping the plant alive. Cells that make up the trunk of a tree are clearly less flexible than cells on a leaf.
Cell walls act in many ways. They serve to protect the plant. They provide support, as well as help in the movement of chemicals and wastes into and out of the cell. More importantly, they control the water that goes in and our. Plants must have good water controlling systems (系统), allowing them to keep water during dry seasons, and get rid of unnecessary water. Plants can’t walk around to find water, so being able to control water is very important.
So there you have it — what a plant cell wall is. Of course, there are many other things that are not talked about here. Knowing more about plant cell walls requires further study and research.
1.The best title of the passage can be .
A. Different Plants B. Different Animals
C. The Plant Cell Wall D. The Uses of Cells
2. From the first two paragraphs we can find that .
A. all plants have a cell wall
B. plant cells and animal cells are the same
C. different kinds of plant have different cell walls
D. there are no differences between the cells of a tree and a dog
3.The underlined word “bent” in the passage is the closest in meaning to .
A. shape-changed B. water-kept
C. sun-burnt D. skin- broken
4. Cells in the trunk of a tree are those on a leaf.
A. as flexible as B. not so flexible as
C. more important than D. less important than
5. What is the most important use of a plant cell wall?
A. to protect the plant.
B. To provide support.
C. To move chemicals and wastes.
D. To control the water.
Late last night, or early this morning, something terrible happened in East Town. Mr Raymond Johnson has lived in East Town and has worked there as a manager for many years. He is forty-two years old, unmarried, and he lives in a big wooden house on Moonlight Road. The people of East Town know Mr Johnson as an unusual man. He does not often leave his house, but his business has made him very rich. Last night, at about midnight, a man who was out walking saw that one of Mr Johnson’s rooms was on fire. He immediately(迅速) called the fire station, and the firemen arrived soon after. It took them half an hour to put out the fire. The firemen were surprised that Mr Johnson did not come out of the house, and two of them went inside to look for him. But Mr Johnson was not in the house. In the bedroom the two men found an open safe(保险箱), which was empty. There were papers on the floor. Mr Johnson’s bedroom windows on the ground floor of the house were open. The firemen also found a set of keys in the room. The police then found out that the keys belonged to Mr Paul White, who visited Mr Johnson at his home yesterday evening. The police are sure that they know the motive(动机)for the crime and are looking for Mr White. The police are puzzled because nobody knows where Mr Johnson is. (每空限填一个单词)
REPORT ON MR RAYMOND JOHNSON’S CASE | |
When | Late last night, or 1. this morning |
2. | Mr Raymond Johnson’s home on 3. Road, East Town |
Who | Victim： Mr Raymond Johnson (a single, 42-year-old manager of great 4. ) Suspect： Mr Paul White |
What | At about midnight, one of Mr Johnson’s rooms 5. fire. It took the firemen 6. minutes to put out the fire. In the bedroom on the ground floor： an 7. open safe； papers on the floor； open bedroom windows； Mr Paul White’s 8. . The police are trying to 9. Mr Paul White. Mr Johnson is 10. , which puzzles the police. |