单选题Passengers are offered money to ______ their seats when planes are overbooked.

单选题We"ve missed the last bus, and I"m afraid we have no ______ but to take a taxi.

单选题 One U.S. dollar is comparable to 131 Japanese yen according to China Daily’s finance news report yesterday.

单选题You can go out, ______you promise to come back before 11 o'clock.

单选题The national compulsory education provides them ______ to economic progress.

单选题Every living thing has an inner biological clock that controls behavior. The clock works all the time; even when there are no outside signs to mark the passing of time. The biological clock tells plants when to form flowers and when the flowers should open. It tells insects when to leave the protective cocoon and fly away. And it tells animals when to eat, sleep and wake. It controls body temperature, the release of some hormones and even dreams. These natural daily events are circadian rhythms. Man has known about them for thousands of years. But the first scientific observation of circadian rhythms was not made until 1729. In that year a French astronomer, Jean Jacques d’Ortous de Mairan, noted that one of his plants opened its leaves at the same time every morning, and closed them at the same time every night. The plant did this even when he kept it in a dark place all the time. Later scientists wondered about circadian rhythms in humans. They learned that man’s biological clock actually keeps time with a day of a little less than 25 hours instead of the 24 hours on a man-made clock. About four years ago an American doctor, Eliot Weitzman, established a laboratory to study how our biological clock works. The people in his experiments are shut off from the outside world. They are free to listen to and live by their circadian rhythms. Dr. Weitzman hopes his research will lead to effective treatments for common sleep problems and sleep disorders caused by ageing and mental illness. The laboratory is in the Montefiore Hospital in New York City. It has two living areas with three small rooms in each. The windows are covered, so no sunlight or moonlight comes in. There are no radios or television receivers. There is a control room between the living areas. It contains computers, one-way cameras and other electronic devices for observing the person in the living area. A doctor or medical technician is on duty in the control room 24 hours a day during an experiment. They do not work the same time each day and are not permitted to wear watches, so the person in the experiment has no idea what time it is. In the first four years of research, Dr. Weitzman and his assistant have observed 16 men between the ages of 21 and 80. The men remained in the laboratory for as long as six months. Last month, a science reporter for “The New York Times” newspaper, Dava Sobel, became the first woman to take part in the experiment. She entered the laboratory on June 13th and stayed for 25 days. Miss Sobel wrote reports about the experiment during that time, which were published in the newspaper.

单选题Vacation policies continue to be a source of______between management and the workers.

单选题I have made ______ I will never go back on my word.

单选题He was ______strict man and he was strict with his work. When he was 36, he was elected ______chairman of the committee.

单选题The young men's balloon flew because the air in it was ______.

单选题If I ______ that your business was growing so rapidly, I wouldn't have been worried about it.

单选题Which of the following statements about Connexion is FALSE?

单选题The bill was passed in the parliament by a majority of 200 votes ______ 30. A. over B. than C. against D. above

单选题The applicants for the position of media director should ______.

单选题My opinion is as good ______.

单选题The term "aerobic exercise" (first line in second last paragraph)is a kind of ______.

单选题In an allergic reaction, the immune system mistakenly ______ a harmless substance as a harmful one.

单选题My sole object was to get shelter ______ the snow, to get myself covered and warm.