题目内容
A black hole is a place in outer space with very strong gravity. Gravity is a great force(力量) that shapes the universe. On Earth, gravity makes apples fall from trees. It keeps your feet planted on the ground. The gravity in a black hole is much stronger. It is so strong that nothing around it can get away from it, not even light.
Black holes are invisible. We can't actually see them because they don’t throw back light. But scientists can find them with space telescopes (望远镜)and special tools. The strong gravity makes nearby stars move in a certain way. By studying how the stars move, scientists can find out if they are flying around a black hole. Strange things happen around black holes. This makes black holes a popular subject of science fiction(科幻) stories, although they are very unreal.
A black hole forms when a star dies. The star falls in on itself and turns into a very small point. Because of its small size and huge mass(质量), the gravity will be so strong that it will pull light in and become a black hole. Black holes can grow huge as they continue to pull other things in and “eat” them. Many scientists believe that there are super-massive black holes at the center of galaxies, including the Milky Way.
The idea of the black hole was first suggested by two different scientists in the 18th century: John Michelle and Pierre-Simon Laplace. In 1967, a physicist named John Archibald Wheeler came up with the name “black hole”. Studying black holes can tell us many things about our galaxy and help scientists answer questions about the universe.
1.The word “invisible” in Paragraph 2 probably means “_________”.
A.far to go B.easy to find C.difficult to catch D.impossible to see
2.The third paragraph is mainly about_________.
A.how big black holes are B.how heavy black holes are
C.how black holes are formed D.how black holes “eat” stars
3.From the passage we learn_________.
A.a star's moving path can help scientists find a black hole
B.writers love writing about black holes because they are real
C.there aren't any black holes at the center of the Milky Way
D.John Archibald Wheeler found the first black hole in space
轻巧夺冠周测月考直通中考系列答案
Lab work is fun but you must be careful. Listen carefully when your teacher reads and explains（解释）the rules before your first lab lesson.
LAB RULES | |
Throughout the lessons | Do not enter the science lab without the teacher's permission(允许）. No food or drinks are allowed in science lab. |
Before the experiment | Read all instructions carefully before every experiment. Prepare all apparatuses (仪器)and put them in right places so that you will not knock them over while doing the experiment. |
During the experiment | If you are unsure how to use the apparatuses or how to operate（操 作）, ask your teacher for help. ? Never smell or taste chemicals（化学药品）unless（除非）your teacher gives permissions. |
After the experiment | Throw waste materials into proper waste baskets Wash all apparatuses after use and return them to the places where they were. Never smell or taste chemicals（化学药品）unless（除非）your teacher gives permissions. |
First Aid | Report all accidents to your teacher immediately. If you spill any chemicals onto your body or clothing, wash with plenty of water and report to your teacher. |
1.You must know the LAB RULES ____________ the first lab lesson.
A.before B.since C.during D.after
2.It is necessary for you to __________ before every experiment.
A.read all instructions carefully B.take enough food and drinks
C.smell chemicals immediately D.talk with your classmates
3.If you are not: sure how to use the apparatuses, __________________.
A.read the rules carefully B.try them again and again
C.ask your teacher for help D.return all apparatuses to the places where they were
4.The underlined word "spill" means ___________________.
A.take care of B.run out of C.fall off D.pour out in drips
5.You should put the waste materials into the ____________.
A.packet B.paper bag C.bin D.waste baskets
6.When you are in the science lab, you mustn't _______________________.
A.be careful in order to prevent injury
B.listen carefully when your teacher explains the rules
C.taste chemicals without the teacher's permission
D.throw waste materials into proper waste baskets