单选题Although buses are {{U}}scheduled{{/U}} to depart at a certain hour, they are often late.

单选题We should never {{U}}content{{/U}} ourselves with a little knowledge only. A. convince B. satisfy C. comfort D. benefit

单选题We"re happy to report that business is booming this year.

单选题Fluoride deters tooth decay by reducing the growth of bacteria that destroy tooth enamel.A. facilitatesB. overwhelmsC. inhibitsD. loosens

单选题Late-night Drinking Coffee lovers beware. Having a quick "pick-me-up" cup of coffeel late in the day will play havoc with your sleep. As well as being a stimulant, caffeine interrupts the flow of melatonin, the brain hormone that sends people into a sleep. Melatonin levels normally start to rise about two hours before bedtime. Levels then peak between 2 a.m. and 4 a. m. , before falling again. "It's the neurohormone that controls our sleep and tells our body when to sleep and when to wake, " says Maurice Ohayon of the Stanford Sleep Epidemiology Research Center at Stanford University in California. But researchers in Israel have found that caffeinated coffee halves the body's levels of this sleep hormone. Lotan Shilo and a team at the Sapir Medical Center in Tel Aviv University found that six volunteers slept less well after a cup of caffeinated coffee than after drinking the same amount of decal. On average, subjects slept 336 minutes per night after drinking caffeinated coffee, compared with 415 minutes after decal. They also took half an hour to drop off-twice as long as usual-and jigged around in bed twice as much. In the second phase of the experiment, the researchers woke the volunteers every three hours and asked them to give a urine sample. Shilo measured concentrations of a breakdown product of melatonin. The results suggest that melationin concentrations in caffeine drinkers were half those in decal drinkers. In a paper accepted for publication in Sleep Medicinc, the researchers suggest that caffeine blocks production of the enzyme that drives melatonin production. Because it can take many hours to eliminate caffeine from the body, Ohayon recommends that coffee lovers switch to decal after lunch.

单选题The captain of the ship ______ the passengers that there was no danger.A. assuredB. ensuredC. securedD. insured

单选题Her faith upheld her in times of sadness.

单选题In judging our work you should {{U}}take into consideration{{/U}} the fact that we have been very busy re cently.

单选题I want to provide my boys with a decent education.

单选题Older citizens in the United States vote more regularly than younger ones, particularly when local and state issues are being considered.A. cast their ballotsB. run for officeC. criticize the governmentD. give their opinions

单选题They attempted to finish the task before July.

单选题Black Holes Most scientists agree that black holes exist but are nearly impossible to locate. A black hole in the universe is not a solid object, like a planet, but it is shaped like a sphere (球体). Astronomers (天文学家) think that at the center of a black hole there is a single point in space with infinite (无限的) density (密度). This single point is called a singularity (奇点). If the singularity theory is correct, it means that when a massive star collapses, all the material in it disappears into the singularity. The center of a black hole would not really be a hole at all, but an infinitely dense point. Anything that crosses the black hole is pulled in by its great gravity. Although black holes do exist, they are difficult to observe. These are the reasons. ●No light or anything else comes out of black holes. As a result, they are invisible to a telescope. ●In astronomical terms, black holes are truly. For example, a black hole formed by the collapse of a giant star would have an event horizon (视界) only 18 miles across. ●The nearest black holes would be dozens of light years away from Earth. One light year is about 6 trillion (万亿) miles. Even the most powerful telescopes could not pick out an object so small at such a great distance. In 1994 the Hubble Space Telescope provided evidence that black holes exist. There are still answers to be found, however, so black holes remain one of the mysteries of the universe.

单选题Before we administer first aid to a victim, it is very important for us

单选题He was rather {{U}}vague{{/U}} about the reasons why he never finished school.

单选题Other countries are also expected to begin clinical gene therapy trials soon.

单选题 阅读下面的短文，文中有15处空白，每处空白给出了4个选项，请根据短文的内容从 4个选项中选择1个最佳答案。 {{B}}Talking to Kids about SARS (非典){{/B}} School age children may be learning about SARS from adults and the media, but may not know what to make of the situation, says a national health charity. The Lung Association says parents should take time to talk to their______(51) and explain the facts about SARS and how to avoid the illness. The following is based on recommendations______(52) Thursday by the Lung Association: ▲ Ask your children if they have heard______(53) SARS at school, from friends, from TV, etc. Finding out what they already know can be a good______(54) to start the conversation and to clear away any wrong ideas they might have about the illness and how it is spread. ▲ School age children are usually old______(55) to understand concepts such as getting sick from germs (细菌) and how to avoid illness. A simple reminder (提示) ______(56) to cough on people and to wash their hands often may be sufficient for younger kids. All children should be shown how to______(57) their hands properly. ▲ Remember to keep it simple so______(58) not to overwhelm children with information, but answer them truthfully. Kids can tell when you're not being honest or if you're hiding something, and sometimes the unknown can be more frightening than the______(59). Parents with anxious children will know______(60) their kids will handle information on SARS and can tailor their discussion accordingly. ▲ One way to explain the illness is to tell children that SARS is like a bad breathing problem. It is______(61) from a cold, but people can catch it in the same ways—such as coughing on someone, not washing your hands or sharing a glass with a sick person. ▲ Describe how SARS is spread, but mention that the chance of______(62) SARS is small. There is no reason to tell children people are dying of SARS ______(63) they ask. Never use the threat of death as a way to remind kids to wash their hands. ▲ Children should be______(64) to trust their parents and other caregivers. Explain that many smart people,______(65) doctors and scientists, are working on the problem and looking out for everyone's health.

单选题Red Meat Links to Higher Risk of Breast Cancer Exercise and keeping a healthy weight are two things that doctors say might help women lower their risk of breast cancer. Mothers may reduce their risk if they breastfeed for at least four months. For older women, hormone replacement therapy can lower the risk of some other diseases. But it has been found to increase the risk of breast cancer. So women should consider their choices carefully. The same may be said for diet. New findings show that younger women who eat a lot of red meat have higher rates of breast cancers called hormone-receptor positive. The growth is fed by the levels of estrogen or another hormone, progesterone, in the body. Researchers at Brigham Women's Hospital in Boston, Massachusetts, reported the findings as part of a health study of nurses. The researchers followed the health of more than 90,000 women from 1991 to 2003. Those who ate the most red meat ate more than one and one-half servings a day. A serving was defined as roughly 84 grams. Those who ate the least red meat ate less than three servings a week. This is what the study found about breast cancers that were hormone receptor-positive: The women who ate the most red meat were almost two times as likely to get them as the women who ate the least of it. Eunyoung Cho, the lead author of the report, says more research is needed to know the reason for the link. But in the past, researchers have suggested that three things may play a part. One is the way meat is cooked or processed. Another is the use of growth hormones in cows. And the third is the kind of iron in red meat. The study appears in the Archives of Internal Medicine. And now we have more to tell you about our subject — resveratrol. We discussed a study in the United States that found that large amounts of this plant compound helped fat mice live longer. The mice were fed much more resveratrol than people could get from red wine, one of the foods that contains it. Now, scientists in France say resveratrol also improves muscle performance — again, at least in mice. They were able to run two times as far in laboratory treadmill tests as mice normally could. The study at the Institute of Genetics and Molecular and Cellular Biology appeared in the

单选题 Can Loud Music Cause Hearing Impairment (损伤)? Have You ever gone to a concert and realized that your seats were right next to the booming speakers? Are you guilty {{U}} {{U}} 1 {{/U}} {{/U}}turning up the volume on your portable cassette or CD player to drown out the whining (哭哭啼啼) of your little brother? Sometimes it's difficult to avoid loud music or noises, but they can be bad news because loud noises can {{U}} {{U}} 2 {{/U}} {{/U}}temporary or permanent hearing loss. Extremely loud music and noises that go on for long periods of {{U}} {{U}} 3 {{/U}} {{/U}}are common causes of deafness. If a noise is so loud that you have to shout to make yourself {{U}} {{U}} 4 {{/U}} {{/U}}, there is a {{U}} {{U}} 5 {{/U}} {{/U}}that the mechanism inside your ear can be injured Temporary hearing loss can happen after you've been {{U}} {{U}} 6 {{/U}} {{/U}}to loud noise for only 15 minutes. If you have temporary hearing loss. you won't be able to hear as {{U}} {{U}} 7 {{/U}} {{/U}}as you normally can, and you may have tinnitus (耳鸣), which is a fancy word for ringing in the ears. Your ears call feel "full", too {{U}} {{U}} 8 {{/U}} {{/U}}these things usually go away and your hearing soon returns to normal. Permanent hearing loss can happen when, someone is exposed to loud noise {{U}} {{U}} 9 {{/U}} {{/U}}and over. Construction workers and people who work in factories must {{U}} {{U}} 10 {{/U}} {{/U}}ear protectors because the equipment they use can be extremely loud. But even some lawn mowers (割草机) and power tools can permanently {{U}} {{U}} 11 {{/U}} {{/U}}a person's ability to hear high-pitched noises and can also give him permanent tinnitus. Listening to extremely loud music over and over call also have the same effect on a person's {{U}} {{U}} 12 {{/U}} {{/U}}. And using headphones on a portable cassette or CD player can be dangerous {{U}} {{U}} 13 {{/U}} {{/U}}if the volume is too high and the headphones are used a lot, the noise can damage the ears. The best way to avoid hearing loss is to wear ear protectors when working with machinery and earplugs when going to a {{U}} {{U}} 14 {{/U}} {{/U}}. Headphones are OK to wear when you're listening to music; just be sure the volume isn't too high, and give them a rest {{U}} {{U}} 15 {{/U}} {{/U}}once in a while.

单选题The council meeting terminated at 2 o"clock.

单选题I want to provide my boys with a decent education.