Which of the following interpretations of the biologists' theory about melatonin is INCORRECT?
A.The production of melatonin in our bodies varies at different times.
B.Melatonin is more likely to cause sleepiness in our bodies.
C.The reduction of melatonin will cause wakefulness in our bodies.
D.The amount of melatonin remains constant in our bodies.

单项选择题紧急呼叫(SOS)需要进行附着以后才能发起的网络服务（ ）

未分类题Which of the following can best sum up the author's overall reaction to her adult son's positive response to spring cleaning?A.Surprised and skeptical.B.Elated and hesitant.C.Relieved and optimistiC.D.Optimistic and hesitant.

单项选择题一组数据的分布曲线呈双峰状态，据此可以推测该组数据中可能有两个（2012年全国统考） A、中数 B、众数 C、平均数 D、几何平均数

单项选择题以下哪些不是交流传动技术的优点 A、功率因数高 B、电机体积、重量小 C、控制技术简单 D、电制动能量可以回馈电网

单项选择题不属于法洛四联症畸形组成的是 A、肺动脉狭窄 B、室间隔缺损 C、主动脉骑跨 D、右心室肥大 E、房间隔缺损

未分类题听力原文： The train I was traveling on was already half an hour latE.I had planned to arrive in Chicago at 7:00 in time to catch the 7:50 train to St. Louis, but there was no hope of that now. I explained the situation to the conductor who advised me to get off before Union Station and take a taxi. When the time came, he even helped me with my languagE.He wished mea good luck as I jumped off, and a few minutes later I was going towards the Union Station in a taxi. It was almost 7:50 when we stopped outside the station, I paid the driver quickly, carried my bags and hurried insidE.'The St. Louis train....'?' was all I had time to say to the first porter I saw. You can imagine my disappointment when he pointed to a train that was just moving out of the station.When did the train he was travelling on arrive in Chicago?A.At 7:00.B.At 7:50.C.In timE.D.Behind its timE.

未分类题Nowadays, a standard for measuring power has changeD.These changes foretell a new standard for measuring power. No longer will a nation's political influence be based solely on the strength of its military forces. Of course, military effectiveness will remain a primary measure of power. But political influence is also closely tied to industrial competitiveness. It's often said that without its military the Soviet Union would really be a third-world nation. The new standard of power and influence that is evolving now places more emphasis on the ability of a country to compete effectively in the economic markets of the worlD.America must recognize this new course of events. Our success in shaping world events over the past 40 years has been the direct result of our ability to adapt technology and to take advantage of the capabilities of our people for the purpose of maintaining peacE.Our industrial prowess (杰出才能) over most of this period was unchallengeD.It is ironic that it is just the prowess that has enabled other countries to prosper(繁荣) and in turn to threaten our industrial leadership.The competitiveness of America's industrial base is an issue bigger than the Department of Defense and is going to require the efforts of the major institutional forces in our society--not be a strong force in the process because we will. But we simply cannot be, nor should we be, liked upon by others as the savior (救星) of American industry.Now a nation's political influence depends on ______.A.the strength of its military forcesB.its ability to compete in industryC.economic marketsD.both A and B

问答题列车司机在列车运行中，应随时检查机车总风缸、[填空(1)] 主管的压力。

单项选择题Listen to the tape and choose the right answer to each question on working at toxic workplaces. What might workers be three times more likely to suffer from? A、the sack B、 adverse conditions C、depression D、demotion

未分类题By saying that 'soccer is an attractive target for gamblers'(Line 1, ParA.2), the author means that gamblers ______.A.are interested in playing soccerB.enjoy watching soccer gamesC.think match results hard to predictD.find match results easy to manipulate