单选题Most viruses that cause swine flu or bird flu are very hard to pass from one human to another: they don't cause epidemics. Sometimes, however, further changes in genes create a virus that can spread rapidly among humans, and can produce a more severe illness. One reason this illness is more severe is that the virus is so new. The regular flu that comes each year is caused by a regular human influenza virus that often has similarities to the viruses that have caused the nu in years past, so people have some degree of immunity to the latest virus. The unusual swine flu or bird flu viruses that develop the ability for person-to-person spread are so different that people have little or no immunity to them. What is the main reason that the swine flu is very dangerous to humans? A. That it is fatal and has killed many. B That it has spread to many countries. C. That people know nothing about it. D. That people have no immunity to it.

单选题The manager allocate duties to the clerks.

单选题Although South Carolina"s mineral resources are abundant , not all of them can be mined lucratively.

单选题Sarah's Uancestors/U arrived here from France about two hundred years ago.

单选题Because he wore a strange collection of clothes and often talked to himself his neighbours considered him Ueccentric/U.

单选题The visitors to the island enjoyed themselves very much, but they refused to eat the Uraw/U fish.

单选题Medical facilities are being upgraded .

单选题It's getting very Udim/U in here. Can you turn on the light, please?

单选题下面有3篇短文，每篇短文后有5道题，每题后面有4个选项。请仔细阅读短文并根据短文回答其后面的问题，从4个选项中选择1个最佳答案。{{B}}第一篇{{/B}} {{B}}Young Female Chimps Outlearn Their Brothers{{/B}} Young female chimps are faster and better learners than young male chimps, suggests a new study, echoing learning differences seen in human girls and boys While young male chimps pass their time playing, young female chimps carefully study their mothers. AS a result, they learn how to fish for tasty termite snacks over two years before the boys. Elizabeth Lonsdorf, now at Lincoln Park Zoo in .Chicago, US, and colleagues at the University of Minnesota, Saint Paul, spent four years watching how young 'chimpanzees in the Gombe National Park in Tanzania learned "cultural behavior". The sex differences in learning behavior were "consistent and strikingly apparent", says the team. The researchers point out that similar differences are seen in human children with regard to skills such as writing. "A sex-based learning differences may therefore date back at least to the last common ancestor of chimpanzees and humans," they write in the journal Nature. Chimps make flexible tools from vegetation and then insert them into termite mounds, extract them and then munch the termites clinging onto the tool The researchers used video cameras to record this feeding behavior and found that each chimp mother had her own technique, such as how she used tools of different lengths; Analysis of the six infants whose ages were known showed that girl chimps were an average of 31 months old when they succeeded in fishing out their termites, Where the boy chimps were aged 58 months on average. Females were also more skillful at getting out more termites with every dip and used techniques similar to their mothers while males did not. Instead of studying their mothers, the boy chimps spent a significantly greater amount of time frolicking around the termite mound. Behaviors such as playing or swinging might help the male infants later in life when typically male activities like hunting or fighting for dominance become important, suggest the researchers. Lonsdorf adds that there are just two main sources of animal portein for chimps -- the termites or colobus monkeys. "Mature males often hunt monkeys up trees, but females are almost always either pregnant or burdened with a clinging infant. This makes hunting difficult," she says. "Adult females spend more time fishing, for termites than males." So becoming proficient at termite fishing could mean adult females eat better. "They can watch their offspring at the same time. The young of both sexes seem to pursue activities related to their adult sex roles at a very young age."

单选题Winston Churchill gave a moving speech.

单选题The organization was {{U}}bold{{/U}} enough to face the press.

单选题 Study Helps Predict Big Mediterranean Quake Scientists have found evidence that an overlooked fault in the eastern Mediterranean is likely to produce an earthquake and tsunami every 800 years as powerful as the one that destroyed Alexandria in AD 365. Using radiocarbon dating techniques, simulations and computer models, the researchers recreated the ancient disaster in order to identify the responsible fault. "We are saying there is probably a repeat time of 800 years for this kind of earthquake," said Ms. Beth Shaw, an earthquake scientist at the University of Cambridge, who led the study. Scientists study past earthquakes in order to determine the future possibility of similar large shocks. Identifying the fault for the AD 365 earthquake and tsunami is important for the tens of millions of people in the region, Ms. Shaw said. The fault close to the southwest coast of Crete last produced a big enough quake to generate a tsunami about 1300, which means the next powerful one could come in the next 100 years, she added in a telephone interview. Ms. Shaw and her colleagues calculate the likely intervals by measuring the motion of either side of the fault to find how often such large earthquakes would have to occur to account for that level of motion, she said. Their computer model suggested an 8 magnitude quake on the fault would produce a tsunami that floods the coastal regions of Alexandria and North Africa, the southern coast of Greece and Sicily all the way up the Adriati to Dubrovnik. This would be similar to the ancient quake in AD 365 that caused widespread destruction in much of Greece and unleashed a tsunami that flooded Alexandria and the Nile Delta, likely killing tens of thousands of people, she said.

单选题We have got to abide by the rules.A. stick toB. persist inC. safeguardD. apply

单选题Mary has blended the ingredients.

单选题 下面有3篇短文，每篇短文后有5道题。请根据短文内容，为每题确定1个最佳选项。{{B}}第一篇{{/B}} 第一篇 Accurate Timer These days time is everything. Between meetings and appointments, deadlines and conference calls, my schedule requires that I know the time down to the minute. Even on weekends, I have a football team to coach, shows to tape and planes to catch. If I'm late, I'm sunk. The problem is that it's hard if my clocks aren't correct. Even the digital clocks can display time inaccurately. Dead batteries, time changes, any of these can cause a clock to be inaccurate. Now there is no need to worry, because advanced radio technology has produced a clock which gets the time directly from the U.S. Atomic Clock in Fort Collins, Colorado, the standard for time-keeping all over the world. The Atomic Clock by Acorn is the most accurate, reliable and convenient timepiece you can have. Every morning at 1:00 a. m, this "smart" clock in Colorado automatically resets itself to the exact hour, minute and second. The U. S. Atomic Clock is accurate to ten billionths of a second per day. This means that the clock deviates less than one second over a one million-year period. The Atomic Clock even adjusts automatically for daylight saving time, so you don't have to remember to "spring forward" or "fall back". The desktop clock model is the only atomic Clock that will not lose time with low power or when you change its batteries. The most accurate clock in the world is of no use if it is difficult to operate. The Acorn Atomic Clock is engineered in Germany using the latest scientific technology. It comes in two styles, the wall clock and the desktop model. Both are designed to be functional and easy to use. The desk clock's display features the exact time (in hours, minutes and seconds), month and date, or you can choose to display any two U. S. or world time zones. It weighs only eight ounces, and is the perfect travel clock It also has dual alarms, perfect for couples. Both the desktop and the wall models have an internal antenna for good reception without unattractive wires.

单选题The author mentions all of the followings as possible products of crude oil EXCEPT _____.

单选题When he got out of the manager's office, from his facial expression we knew that his proposal must have been Uturned down/U.

单选题It isn"t easy to put up with people who are impolite.

单选题These programs are of immense value to old people.

单选题You have to be patient if you want to sustain your position.