单选题Diamond is the hardest known substance, so diamonds can be cut only by another diamonds.

单选题Buses were developed at the beginning of the twentieth century to compete with streetcars by providing flexibility greater in routes.

单选题The word "distinct" in line 17 is closest in meaning to

单选题Germ theory defined precisely how diseases affect tissues and described their passage from one living creature to other

单选题According to the passage, which of the following was a possible motive for the cultivation of plants in eastern North America?

单选题It can be inferred from the passage that theropods were

单选题Lucid dreaming, the ability dreamers to become aware of and to control their dreams while dreaming, is the focus of some current psychological research.

单选题Visibly only through large telescopes, Pluto has a yellowish color, which indicates that there is very little atmosphere.

单选题Whataspectofanimalexperimentationdoestheprofessormainlydiscuss?

单选题Wild eagles that survive to adulthood are believed ...... from 20 to 30 years. (a)live (b)to live (c)they live (d)their living

单选题The technique of spectroscopy allows (analyst) of incoming light after it (has been) separated into (its) component wavelengths (by passage) through a prism.

单选题Listen to Track 43. A. To acknowledge that he cannot go to this year's career fair B. To acknowledge the amount of preparation he will have C. To indicate that he has school work he must complete before the career fair D. To indicate that he needs to go to his job now

单选题Under (the certain) conditions, a rainbow appears at the end (of) a (rain shower) (in the quarter) of the sky opposite the Sun.

单选题Listening1"LearningCenter"

单选题The nineteenth-century romantic movement in art was partially a reaction to what was perceived as overemphasis on reasonable and order in neoclassicism.

单选题Sleek and powerful swimmers found to all seas, dolphins are distinguished from A B C porpoises by well-defined, beaklike snouts and conical teeth. D

单选题All of the following words are defined in the passage EXCEPT

单选题{{B}}Listening Comprehension Section Directions{{/B}} This section measures your ability to understand conversations and lectures in English. You will hear each conversation or lecture only one time. After each conversation or lecture, you will answer some questions about it. The questions typically ask about the main idea and supporting details. Some questions ask about a speaker's purpose or attitude. Answer the questions based on what is stated or implied by the speakers. You may take notes while you listen. You may use your notes to help you answer the questions. Your notes will not be scored. If you need to change the volume while you listen, click on the {{B}}Volume{{/B}} icon at the top of the screen. In some questions, you will see this icon:. This means that you will hear, but not see part of the question. Some of the questions have special directions. These directions appear in a gray box on the screen. Most questions are worth one point. If a question is worth more than one point, it will have special directions that indicate how many points you can receive. You must answer each question. After you answer, click on {{B}}Next{{/B}}. Then click on {{B}}OK{{/B}} to confirm your answer and go on to the next question. After you click on {{B}}OK{{/B}}, you cannot return to previous questions. You will have 20 minutes to answer the questions in this section. A clock at the top of the screen will show you how much time is remaining. The clock will not count down while you are listening to test material. {{B}}Click on Proceed to continue.{{/B}} To change the volume, click on the {{B}}Volume{{/B}} icon at the top of the screen. The volume control will appear. Move the volume indicator to the left or to the right to change the volume. To close the volume control, move the mouse pointer to another part of the screen. You will be able to change the volume during the test if you need to.{{B}}Set 1 Conversation: Lecture Arrangements{{/B}}{{B}}Narrator{{/B}} Listen to a part of a conversation about Lecture Arrangements between a student and a teacher.

单选题The word "appealing" in line 22 is closest in meaning to

单选题THE ORIGIN OF THE UNIVERSE 1 Astronomers believe that the universe began with a large, dense mass of gas consisting mainly of hydrogen, the simplest of all the naturally occurring chemical elements. The mass of hydrogen was very hot and caused intense light and much expanding motion. As the universe expanded, its light became dimmer, yet even now some of the primeval light may be present. 2 The original universe underwent a physical transition that gradually differentiated it into galaxies, stars, and planets. As the original mass of gas expanded and cooled, large clouds separated themselves from the parent mass. Gravity played an important role in this mechanism. Matter is subject to gravity, yet matter is also the cause of gravity since it is matter's mass that determines the strength of the gravitational force. 3 Scientists believe that the original mass of gas in the universe was not completely uniform, and there were some regions that were slightly denser and capable of generating stronger gravitational fields than others. Since gravity tends to pull matter together, the denser regions tended to become even more compact. Thus, small variations in the original mass evolved into denser clouds that gradually separated from the expanding parent mass. From these clouds, the galaxies were formed. 4 At the end of the first phase of the universe, a great number of huge clouds had become separate entities that could start their own independent evolution. These turbulent clouds-- ancient galaxies-contained variations that grew in importance over time. The clouds divided into smaller and smaller "cloudlets" that gravity caused to contract. The increase in pressure from this contraction caused the temperature to rise until the cloudlets began to glow as individual, luminous stars. 5 Astronomers believe that the earliest galaxies were small when they formed most of their stars, but accumulated most of their mass later through collisions. Large galaxies formed in stages as smaller galaxies were attracted to one another by gravity. As the smaller galaxies were pulled together over time, they merged into larger and larger structures, eventually forming massive galaxies. As many as half of all galaxies are thought to have been involved in some sort of collision.