单选题Williams had not been there during the ______ moments when the kidnapping had taken place. A. superior B. rigorous C. vital D. unique

单选题Speaker A: Remember me to David, won't you?Speaker B:______

单选题He always did well at school _____ having to do part-time jobs every now and then.

单选题Small dogs generally live longer than big dogs so that a small Yorkshire terrier (猎狐狗) next door could be around for a long time. But body size isn't the only factor that 18 how long dogs survive. Personality influences life span, too, according to a new study that might help explain how animal 19 evolve. Study on animals from ants to apes has found that different 20 have different personalities. Some are timid, others 21 . Biologists have proposed that temperaments (性情) evolved along with life history. Bold, violent animals use a lot of energy fast in 22 short lives, the thinking goes, whereas calmer animals last longer, saving themselves to 23 later in life. But it's hard to run evolutionary researches on these personalities in anything longer lived than a fruit fly. So evolutionary biologist Vincent from Canada 24 an idea about dogs. 'All these breed differences reflect an experiment on artificial selection,' says Vincent. The huge diversity of dogs resulted not from natural selection, but from generations of humans selecting animals with traits they wanted—the ability to chase foxes into holes, or herd sheep, or sit 25 on a sofa. But evolutionary physiologist Joseph Williams of Ohio State University in Columbus isn't 26 that what happened in dogs has anything to do with evolution in nature. 'For me, it still remains to be seen. Dogs are contrary to what you would expect in nature 27 longevity,' he says. Elephants can live for decades, whereas a mouse might make it through only for several seasons. On the other hand, a Chihuahua will generally outlast a Saint Bernard.

单选题I was surprised to find his article on such an______ topic so ______.

单选题[此试题无题干]

单选题For Sauces not only used his ______ in the hold up, but also made his get-away in his own easily recognized family car.

单选题 ______ the population of China? I dont know the exact number, but I know it has ______ population. A．How much/much B．Whats/a large C．How many/many D．Whats/many

单选题This book will show you ______ can be used in other contexts. A. how you have observed B. how what you have observed C. that you have observed D. how that you have observed

单选题They continued to ______ about and enjoy themselves until they became tired. A. stroke B. stroll C. stammer D. string

单选题______ work has been done to improve people' s living standard.

单选题Artificial hearts have long been the stuff of science fiction. In "Robocop", snazzy cardiac devices are made by Yamaha and Jensen, and in "Star Trek", Jean-Luc Picard, captain of the Enterprise, has one implanted in the year 2328. In the present day, however, their history has been more chequered. The first serious attempt to build one happened in the 1980s, when Jarvik-7, made by Robert Jarvik, a surgeon at the University of Utah, captured the world's attention. But Jarvik-7 was a complicated affair that needed to be connected' via tubes to machines outside the body. The patient could not go home, nor even turn around in bed. Various other designs have been tried since, but all were seen as temporary expedients intended to tide a patient over until the real thing became available from a human donor. That may be about to change. This week, America's Food and Drug Administration gave its approval to a new type of artificial heart made by Abiomed, a firm based near Boston. The agency granted a "humanitarian device exemption", a restricted form of approval that will allow doctors to implant the new device in people whose hearts are about to fail but who cannot, for reasons such as intolerance of the immunosuppressive drugs needed to stop rejection, receive a transplant. Such people have a life expectancy of less than a month, but a dozen similarly hopeless patients implanted with Abiomed's heart survived for about five months. Unlike Dr. Jarvik's device, this newfangled bundle of titanium and polyurethane alms to set the patient free. An electric motor revolving up to 10 000 times a minute pushes an incompressible fluid around the Abiomed heart, and that fluid, in turn, pushes the blood--first to the lungs to be oxygenated, and then around the body. Power is supplied by an electric current generated in a pack outside the body. This induces current in the motor inside the heart. All diagnostics are done remotely, using radio signals. There are no tubes or wires coming out of the patient. The charger is usually plugged into the mains, but if armed with a battery it can be carried around for hours in a vest or backpack, thus allowing the patient to roam freely. Most strikingly, the device's internal battery can last half an hour before it needs recharging. That allows someone time to take a shower or even go for a quick swim without having to wear the charger. Abiomed's chairman, Michael Minogue, does not claim that his firm's product will displace human transplants. Even so, the firm has big ambitions. It is already developing a new version that will be 30% smaller (meaning more women can use it) and will last for five years. That should be ready by 2008--320 years earlier than the writers of "Star Trek" predicted.

单选题As there was not enough money to bury all dead AIDS {{U}}orphans{{/U}}, 23 babies were interred in a modest cemetery in South Africa before World AIDS Day.

单选题She is______a driver as any one else.

单选题Spiders "hold their planetary seat with assurance" because they are ______.

单选题Digging the garden with a spade is a very ______ task. I am exhausted after such two-hour's work.

单选题Between the two mounts ______ and they decide to build a ropeway(索道).A. lies a very deep valleyB. does a very deep valley lieC. a very deep valley liesD. a very deep valley lays

单选题 Thanks to Science, You Can Eat an Apple Every Day A. Walk into a U.S. supermarket on any given day and you're pretty much guaranteed to find apples. In our globalized economy, we expect nothing less than to be able to consume our favorite fruits and vegetables all year, even when they're not in season locally. Placing strawberries from Mexico in your shopping cart in February and stocking up on kiwis (猕猴桃) from Chile in July—that's pretty much normal, even expected. B. But to buy an apple in March? That's a whole different story. We rarely need to go overseas for that. Only 5 percent of the apples consumed in the U.S. are imported, according to the U.S. Apple Association. That means most of our apples are picked from trees in Washington, New York, or Michigan—three of the country's largest apple-producing states—and they are picked during fall harvest. C. Harvest season for apples in the U.S. depends on the variety and the state, falling somewhere between early August and mid-November. So if it's March, your apple was likely harvested months ago. Yet it still tastes pretty fresh. This wasn't always the case. 'It's something we take for granted now,' says Chris Watkins, a professor of horticulture (园艺) at Cornell University and the director of Cornell's cooperative extension. During harvest season, Watkins and post-doctoral students drive a truck to farms all over New York State to collect apples and bring them back to their lab at Cornell. There they study how the apples react under different storage conditions. D. According to Watkins, we have a technology called Controlled Atmosphere (CA) storage to thank for being able to eat an apple whenever we please. In CA storage rooms, the temperature, oxygen, carbon dioxide, and humidity levels are adjusted to form hospitable hibernation environments for apples being stored after harvest. The perfect combination of temperature and gases, which differs for each variety, allows apples to stay fresh for longer after harvest than if they were simply refrigerated. Commercially refrigerating apples only preserves the fruit for a few months before it gets soft and dehydrated. And just keeping them in your home refrigerator? They'll likely only stay fresh for a few weeks. E. The concept of controlled atmosphere storage is not entirely new—modified atmosphere storage for food dates back to the 1800s. But the motivation of research for the facilities that we have today came from Cambridge University in the 1920s. The technique was improved when Robert Smock, a researcher in Cornell University, visited Cambridge in the late 1930s to observe the groundbreaking CA technology developed there. Smock, who studied post-harvest technologies for apples, pears, plums, and peaches, was trying to figure out how to extend the shelf life of the fruits. Smock brought what he learned back to New York and adapted CA to work for local apple varieties, focusing on how to make apples last until the spring. In his laboratory half-hidden in a barn near Cornell, Smock experimented by placing apples in sealed rooms at different temperatures and with various mixtures of oxygen and carbon dioxide to see how the fruit would respond. As a result of Smock's work, the first CA rooms in the U.S. were built in New York in the 1950s, and shortly after, the apple consumption season extended to the springtime nationwide. F. Controlled atmosphere is so widespread today that Watkins estimates that almost every apple you see in a grocery store out of season will have been, at some point in its lifetime, subjected to it. 'The apple industry as we know it today would not exist without CA,' Watkins says. G. The Crist family farm in the Hudson Valley, New York, is just one example. Jeff Crist is a fourth-generation apple farmer and storage facility manager at Crist Brothers Orchards. He estimates his family built their first CA storage facility shortly after Smock made his post-harvest research available for commercial use at Cornell, just an hour's drive away. At the orchard, 400,000 apple trees line different patches of the 550-acre property. The Crists grow apples for large retailers and grocery stores east of the Mississippi River from Florida to Maine—think Giant and Costco. H. And their storage facility allows them to get all of these apples to market when there's demand, not just in the fall. The Crists' CA storage facility has 30 rooms, each one 40- by 80-feet with 20-foot-high ceilings. The rooms are sealed with foam panels and lined with modem sliding doors. Each of the 30 controlled-atmosphere rooms can fit a bunch of apples—1,400,000 to be exact. The rooms fill up quickly during harvest time when employees bring in loads from the fields. I. Then, when the doors slide shut, Crist turns on the CA system right from his iPad. With the touch of his finger, he activates the coolers, lowers the oxygen in the room to about 1.5 to 2.5 percent (the oxygen around is about 21 percent), and adjusts the carbon dioxide, essentially putting the apples to sleep. When they're surrounded by less oxygen and more carbon than found in air, apples don't have enough energy to complete the ripening processes, says Jim Mattheis, a researcher at the USDA's Tree Fruit Research Laboratory located in Wenatchee, Washington. That's because like humans, apples breathe, taking in oxygen and releasing carbon dioxide. J. Sleepier apples have slower respiration rates and stay firm, colorful, flavorful and nutritionally dense for longer. The trick is to avoid bringing the oxygen levels too low, otherwise the apples will ferment. But not all apples ripen quite the same way, so figuring out the right way to do CA is kind of like a puzzle. 'Apples are like people—they are not all the same. One recipe for growing doesn't work with all the different varieties, and it's the same in the post-harvest environment,' Mattheis says. Some varieties are notoriously trickier to care for. For example, Honeycrisps are sensitive to low temperatures so you can't put them in cold environments right after they've been harvested. And Fujis don't always react well to high carbon dioxide levels, so you have to monitor them closely. K. With new apple varieties being developed frequently, post-harvest researchers like Watkins and Mattheis are hard at work. In their labs they test out what type of CA environment works best for these newly bred varieties. Then they take their research to growers like Crist so that when they open their CA rooms as the market demands, their apples are good-looking and tasty.

单选题The train ______ of the station right on time.

单选题The conclusion can be drawn from the text that Britain's public services may be