单选题According to the American federal government, residents of Hawaii have the longest life ______.

单选题Ford proposed a system ______ each worker would have a special job to do.

单选题The pilot asked all the passengers on board to remain ______ as the plane was making a landing.

单选题The science behind solar (太阳的) energy is not new. But Sheridan Community Schools is the first school district in Indiana to be completely solar-powered. The district finished installing solar panels (太阳能板) for all three of its schools in 2016. Some of the panels can turn to follow the sun across the sky. Sheridan"s solar push is part of a trend. In 2008, fewer than 1,000 schools used solar power. By 2014, there were 3,727 schools with solar panels in the US. This data comes from a report by the Solar Foundation, an organization that promotes the use of solar power. Roxie Brown, a program director there, says that the number of Schools with solar panels has continued to rise since 2014. （79） Solar power has some obvious advantages over other energy sources. Sunlight is a renewable (可再生的) resource, which means it won"t run out. Solar panels don"t harm the environment. Also sunlight is free. So by using solar power, schools can save money on energy costs over time. But switching to solar power isn"t always easy. Solar panels can be expensive to install. Sherdan Community Schools had to borrow money to pay for its solar transition. （80） The panels also take up space. But for many schools, going solar is worth it. The use of solar energy can also help students learn about electricity and environmental issues. Teachers at schools that use solar power often incorporate it into their science lessons. The kids talk about it in the classroom. Then they can look at it in action. According to Brown, the educational impact of solar panels is "the most compelling reason" for schools to install them. Brown hopes the panels will give Sheridan students a global perspective. "The world is bigger than the boundaries of their school district," he says. "They"re doing things to help the world as a whole."

单选题Music comes in many forms; most countries have a style of their own. (56) the turn of the century when jazz was born, America had no prominent (57) of its own. No one knows exactly when jazz was (58) , or by whom. But it began to be (59) in the early 1900s. Jazz is America's contribution to (60) music. In contrast to classical music, which (61) formal European traditions, jazz is spontaneous and free form. It bubbles with energy, (62) the moods, interests, and emotions of the people. In the 1920s jazz (63) like America, and (64) it does today.The (65) of this music are as interesting as the music (66) American Negroes, or blacks, as they are called today, were the jazz (67) They were brought to Southern States (68) slaves. They were sold to plantation owners and forced to work long (69) When a Negro died his friend and relatives (70) a procession to carry the body to the cemetery. In New Orleans, a band often accompanied the (71) On the way to the ceme-tery the band played slow, solemn music suited to the occasion. (72) on the way home the mood changed. Spirits lifted. Death had removed one of their (73) , but the living were glad to be alive. The band played (74) music, improvising (即兴表演) on both the harmony and the melody of the tunes (75) ,at the funeral.This music made everyone want to dance. It was an early form of jazz.

单选题The market investigation is indispensable to sales promotion. They are as closely related as the lips and teeth, so to speak. What you produce is for sale on the market. It would be impossible to succeed in selling a product without first investigating the market. In the international market, goods on sale coming from different countries and suppliers are always facing keen competition. Under such circumstances, they will try everything possible to familiarize themselves with the market conditions. In making investigations, we ought to get information about what similar items the competitors are offering on the market, what prices they are quoting (报价), what features their products have, who are their regular customers, etc. Then, how can we obtain such information? There are many channels that we can make use of in doing this sort of work. The commercial counselor's offices of our embassies stationed abroad can help us in making market investigations. Nowadays, our import and export corporations send their trade groups abroad every now and then. One of their purposes is to make market surveys on the spot. Certainly, face-to-face talks with foreign businessmen are also important channels to get market information. The Chinese Export Commodities Fairs and some other fairs of similar nature as well as visits of foreign businessmen provide us with such opportunities. Of course, there are some other ways of making market investigations.

单选题Professor Li, who I ______ abroad, still teaches in Peking University.

单选题Universities generally ______ their students from among the high school graduates.

单选题How long do you think ______ to finish this urgent task?

单选题We stored up some food and water ______ things got worse.

单选题Peter: Hello, I"m Peter Smith. Aren"t you new here? Wendy: ______ I transferred from UCLA.

单选题Please don"t come here today. I would rather you ______ tomorrow.

单选题All students are ______ to the rules of the school.

单选题With the bridge ______, there was nothing for it but to swim.

单选题The other day, my brother drove his car down the street at ______ I thought was a dangerous speed.

单选题Hardly had he finished his speech ______ the audience started cheering.

单选题The earthquake happened in ______.