1-Nearly 4 million people in the United States and 170 million worldwide are believed to be infected with the hepatitis C virus. Long-term infection is the __________ cause of liver disease in the United States and, once it causes liver ____________, the leading cause of liver transplants.
2-Hepatitis C usually comes from sharing ___________ or through unprotected sex, although some infections can be traced to a ___________ of contaminated blood. Blood banks now have screening tests for the virus.
3-Another wetter spell that lasted from about 750 A.D. to 900 A.D. coincided with ____________ expansion. During this time, the native people moved from so-called pit houses, which were circular, covered pits used as shelters and storage areas, into above-ground ____________.
4-The onset of a significantly drier climate in about 1330 A.D. coincided with ____________ of higher elevation dwellings and population _____________ to river areas.
5-The partridge pea is unable to adapt itself quickly ____________ to keep pace with the changing conditions, leaving it and possibly other native plants _____________ the verge of extinction, the researchers found.
6-Writing in the journal Science, the researches found seed production by Minnesota plants dropped 84 percent ___________ grown in Kansas and 94 percent when grown in Oklahoma, __________ conditions are warmer and drier. 7-With U.N. agencies planning for the possible arrival of another million Afghan refugees in Pakistan ____________ drought and the current crisis, the doctors said they feared the virus could spread _____________ among the newcomers.
8-The original smallpox vaccine, ____________ has its origins in the 18th century, was simply a dose of the cattle disease cowpox ____________ seemed to give smallpox immunity to dairy maids. Cultivated in calves, it falls short of modern safety requirements.
9-From small towns in the heartland of the United States to major European capitals, demand __________ the masks has soared ____________ the suicide attacks on the World Trade Center and Pentagon.
10-Shaw and co-author Julie Etterson of the University of Virginia planted seeds from the Minnesota partridge pea in Kansas, ___________ temperatures are about 7 degrees warmer ____________ the plant's native state.
11-___________ the right training, users can be lulled into a false sense of security -- or even suffocated by the mask itself if, ___________ some Israelis did during the Gulf War a decade ago, they fail to remove the protective seal before putting it on.
12-``Far more important is that most people ___________ they acquire a mask will probably not be guided through the process of ____________ it is the correct mask for the job that they want it for. They are also unlikely to get a mask with the proper maintenance history,'' Davey added.
13-___________ a car, gas masks need to be kept in the best working order for maximum protection. The rubber on the mask can become stiff with time and lose _____________ flexibility. The seal, gaskets and the filter canister must be checked to make sure they are still working.
14-People must also make sure the canister is designed to filter out the right substances and has been stored ________________. _____________ shelf life is limited.
15-Thirty-four states in the USA three-stage licensing systems ___________ 16-year-olds initially can drive only with an adult in the vehicle, then alone only outside peak crash times. If they do not receive any traffic violations, they win the right to drive ____________ they please.
16-University of Michigan, researcher Jean Shope, _____________ study produced similar findings in Michigan, said the graduated licensing system was effective, _____________ it did not alter teen-age drivers' rate of alcohol-related crashes.
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