[单项选择]Some plants are very _________ to light; they prefer the shade.
A. sensible
B. flexible
C. objective
D. sensitive

[单项选择]Some plants are very __________ to light; they prefer the shade.
A. sensible
B. flexible
C. objective
D. sensitive

[单项选择]Nuclear power plants are some of the largest producers of （） wastes, with each plant producing barrels of radioactive material that must be stored in special protective containers.
A. biodegradable
B. hazardous
C. reasonable
D. durable

[单项选择]Light travels very fast. It moves at a speed of 300,000 kilometers a second. Light reaches us from the moon in less than a second and a half. The moon is about 382,000 kilometers away.
Light from the sun reaches us in 8.5 minutes. The sun is about 149,840,000 kilometers from the earth.
The other stars are farther away than the sun. Light from the nearest star reaches us in about four years. When you look at a star, you do not see its present condition. You see it as it used to be. Light from some stars takes hundreds of years to reach us. We never see a star as it is now. We see it as it was long ago; perhaps hundreds of thousands of years ago.
Astronomers (天文学家) watch the stars through big telescopes. The world’s biggest telescope is in Russia. The next biggest is in-the United States. With these great telescopes astronomers can see stars and other things very far away. Some of these things are not only stars. They are great groups of stars.
The light of the sun reac
A. more time than
B. less time than
C. as much time as
D. less years than

[单项选择]Some very rare drawings have been recovered for this exhibition through ______ research work in museums and libraries.
A. plain
B. minor
C. assiduous
D. flexible

[填空题]There are some very good things about open education. This way of teaching allows the students to grow as people, and to develop their own interests in many subjects. Open education allows students to be responsible for their own education, as they are responsible for what they do in life. Some students do badly in a traditional classroom. The open classroom may allow them to enjoy learning. Some students will be happier in an open education school. They will not have to worry about grades or rules. For students who worry about these things a lot, it is a good idea to be in an open classroom.
But many students will not do well in an open classroom. For some students, there are too few rules. These students will do little in school. They will not make good use of this type of education. Because open education is so different from traditional education, these students may have a problem getting used to making so many choices. For many students it is important to have some rules in