单选题While nuclear weapons present grave ______ . dangers, the predominant crisis of over population is with us today. A. inevitable B. constant C. overwhelming D. potential

单选题Don't say anything more about it to others, or you'll ______ it even worse than before.

单选题We may infer that a change in class relationships after the close of the Middle Ages produced greater productivity because ______.

单选题No other newspaper columnist has managed {{U}}as yet{{/U}} to rival Ann Landers' popularity in terms of readership.

单选题She felt offended at my remarks, but it wasn't my ______ to hurt her. A. intent B. scheme C. intention D. meaning

单选题 Jack ran quickly to his dormitory, three books ______ under his arm.

单选题According to the passage, which of the following is NOT true?

单选题The trumpet player was certainly loud. But I wasn't bothered by his loudness ______ by his lack of talent. A. than B. more than C. as D. so much as

单选题The author mentions Kleck, kott, and Bellesiles mainly to ______.

单选题We learn from the second paragraph, ______.

单选题It is important that enough money ______ to fund the project.

单选题Those regions inhabited mostly by national minorities in the Northwest of the country are retarded in terms of social progress and economic development ______ the coastal provinces.

单选题Scientists claim that air pollution causes a decline in the world' s average air temperature. In order to prove that theory, ecologists have turned to historical data in relation to especially huge volcanic eruptions. They suspect that volcanoes effect weather changes that are similar to air pollution. One source of information is the effect of the eruption of Tambora, a volcano in Sumbawa, the Dutch East Indies ( the former name of the Republic of Indonesia) ,in April 1815. The largest recorded volcanic eruption, Tambora threw 150 million ton of fine ash into the stratosphere. The ash from a volcano spreads worldwide in a few days and remains in the air for years. Its effect is to turn in coming solar radiation into space and thus cool the earth. For example, records of weather in Eng land show that between April and November 1815, the average temperature had fallen 4.5°F during the next twenty-four months, England suffered one of the coldest periods of its history. Farmers' re cords from April 1815 to December 1818 indicate frost throughout the spring and summer and sharp decreases in crop and livestock markets. Since there was a time lag of several years between cause and effect, by the time the world agricultural commodity community had deteriorated, no one realized the cause. Ecologists today warn that we face a twofold menace. The ever-present possibility of volcanic eruptions, such as that of Mt. St. Helens in Washington, added to man' s pollution of the atmosphere with oil, gas, coal, and other polluting substances, may bring us increasingly colder weather.

单选题We should ______ all advanced science and technology to develop our economy.

单选题-- How much is your new computer ______?-- 12,000 Yuan.

单选题We have made up our minds and nothing can prevent us ______ on the experiment.A. from carried B. from being carriedC. carrying D. to carry

单选题Computer brain games may not offer the big mental boost many were hoping for, suggests new research, but brain scientists and brain-game experts don't all agree on the findings. The study, out this week in Nature, is the largest of its kind, say scientists from England's Medical Research Council Cognition and Brain Sciences Unit and the Alzheimer's Society, UK. They said in a Tuesday press briefing that brain-training games, used by millions, may not increase general brain power on other tasks or increase IQ "Participants did get better at games they practiced. The more they trained, the better they got. But there was still no translation to any general improvement in cognitive function," said lead author Adrian Owen, assistant director of Medical Research Council. The online experiment was sponsored by the BBC and involved more than 11 000 people between the ages of 18 and 60. They were split into three groups, including two groups that played different brain-training games that are similar to commercially available games, and a control group that was asked to go online and find answers to questions about topics such as music. Participants trained for at least 10 minutes a day, three times a week, for up to six weeks, Owen said. All took standard cognitive assessment tests at the start and finish of the study. While players increased their skills the more they played a specific game, that improvement didn't transfer to other activities or to a higher score on intelligence tests, said Owen and colleagues. Duke psychiatrist and Alzheimer's expert Murali Doraiswamy said it's the best study done to date and a good reality check. "There was so much hype surrounding brain games," he said. But it's not a death knell for gaming, Doraiswamy said. "I still think brain games offer tremendous potential for helping people with conditions such as ADHD and learning disabilities, but this study puts the burden of proof now on game manufacturers to show that they really offer meaningful benefits. " Study shortcomings include the fact that it didn't focus on the aging population, a group targeted by brain-game makers, experts said. And it did not look at benefits of more intense training, said Alvaro Fernandez, CEO and cofounder of Sharp Brains, a San Francisco market research firm that specializes in cognitive science. "This study shows random brain exercise doesn't transfer, but it does not deny that transfer can work if a person engages in more intense and targeted brain-training," Fernandez said.

单选题The old-fashioned chair in the living room has been ______ from my great grandmother.