题目列表(包括答案和解析)
阅读理解
Every object has weight. But the center of its weight is not always in the middle of the object, If the top of an object is heavier than its bottom, it will fall over easily. We say that its center of gravity
(引力)is high. But if the bottom is heavier, it won't fall easily. Then we say that its center of gravity is low.Look at the first picture, lifts empty box must fall over, bemuse its center of gravity (C) is not above the line of its bottom (AB).
Now look at the second picture. There is some heavy iron at the bottom of this box. It will not fall, because its center of gravity is above its bottom.
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(1) Please point out which box will not fall?
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(2) From the passage, we can infer that the Leaning Tower of Pisa does not fall is because_______.
[
]A
.the top of the tower is heavier than its bottomB
.the bottom of the tower is not heavier than its topC
.its center of the gravity is still above the line of its bottomD
.its center of the gravity is not above the line of its bottom(3) If an object has a low center of gravity, _______.
[
]|
A .it won't fall |
B .it won't fall easily |
|
C .it is certain to fall over |
D .its top must be heavier |
(4) Which of the following is TRUE according to the passage?
[
]A
.The center of the weight is always in the middle of the objectB
.The center of the weight is always on the objectC
.The center of gravity is not always in the middle of the objectD
.The center of the gravity is always high(5) The passage is mainly about _______.
[
]|
A .why things fall over |
B .a low center of gravity |
|
C .a high center of gravity |
D .that everything has weight |
John likes playing soccer very much and he _____ about one hour playing it every day.
A. spent B. wil spend C. has spent D. spends
| A.meet the old man | B.compare his heart with others’ |
| C.show his beautiful heart | D.give pieces of his heart to others |
| A.a sily man | B.a humorous man |
| C.a wel-known man | D.a kind-hearted man |
| A.lost | B.moved | C.hurt | D.untouched |
| A.he didn’t expect others’return |
| B.he didn’t feel pain |
| C.he didn’t think it serious |
| D.he cared nothing |
| A.ideas | B.scars | C.love | D.beauty |
| A.before | B.since | C.during | D.after |
| A.taste the chemicals first |
| B.clean al the apparatus |
| C.read al instructions carefuly |
| D.report al the accidents to the teacher |
| A.bring food into the lab | |
| B.enter the lab anytime | |
| C.smel chemicals as you like | D.learn science directly in the lab |
| A.Before the Experiment |
| B.First Aid |
| C.During the Experiment |
| D.After the Experiment |
Laboratory work is your chance to learn science firsthand. It can be fun but you must be careful to prevent injury. Listen closely when your teacher reads and explains the rules before your first lab lesson.
LABORATORYRULES
Throughout the lesson
·Do not enter the science lab without the teacher’s permission.·No food or drinks are to be alowed in the science lab.
Before the Experiment
·Read al instructions carefuly before every experiment.
·Prepare al apparatus(仪器)and arrange them so that you wil not knock them over while doing the experiment.
During the Experiment
·If you are unsure of how to use any apparatus or how to operate, ask your teacher for help.·Never smel or taste chemicals unless your teacher gives permission.
After the Experiment
·Wash al apparatus after use and return them to the places where they were.
·Throw waste materials in proper waste baskets. First Aid
·Report al accidents to your teacher immediately.
·If you spil( 溅 出 )any chemicals onto your body or clothing, wash with plenty of water and report to your teacher.
1. Your teacher wil probably tel you the rules above _____ the first lab lesson.
A. before B. since C. during D. after
2. Before every experiment, you should _____.
A. taste the chemicals first
B. clean al the apparatus
C. read al instructions carefuly
D. report al the accidents to the teacher
3. When you are not sure how to use al apparatus, _____.
A. try them on your own
B. read the rules carefuly
C. ask your teacher for help
d. put them back
4. It is clear that you can _____.
A. bring food into the lab
B. enter the lab anytime
C. smel chemicals as you like
D. learn science directly in the lab
5. If you get chemicals on the clothing, you can find ways to solve it in the part _____.
A. Before the Experiment
B. First Aid
C. During the Experiment
D. After the Experiment
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