问题
单项选择题
下列关于水蛭性状的说法正确的是（）
A.体扁平，背部有黑色斑点排成5条纵线，两端各具1吸盘
B.体扁平，背部有红色斑点排成6条纵线，两端均无吸盘
C.体圆，背部有黑色斑点排成5条纵线，1端具1吸盘
D.体扁平，背部有橙黄色斑点排成5条纵线，顶端具1吸盘
E.体圆，背部有黑色斑点散在，两端各具1吸盘
答案
参考答案：A
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下列关于水蛭性状的说法正确的是（）
A.体扁平，背部有黑色斑点排成5条纵线，两端各具1吸盘
B.体扁平，背部有红色斑点排成6条纵线，两端均无吸盘
C.体圆，背部有黑色斑点排成5条纵线，1端具1吸盘
D.体扁平，背部有橙黄色斑点排成5条纵线，顶端具1吸盘
E.体圆，背部有黑色斑点散在，两端各具1吸盘
参考答案：A
| 阅读理解。 |
| Many people think it is safe to use a cell phone while they are driving. Yet Scores of studies suggest that real multitaskers - those who can carry out multiple (多个的) tasks equally well, make up just 2 per cent of the population. More surprisingly, the so-called "supertaskers" actually have differently structured brains to the other 98 percent. The brain areas that make supertaskers differ from the rest of the population are the same parts that are most different between humans and nonhuman primates (灵长类), according to David Strayer, director of the applied cognition lab at the University of Utah. Scientists are unsure of the reason why some brains are different. In fact, we could all benefit from doing just one task at once. In most of us, scientists have located a "bottleneck in the brain" that may explain why we find it hard to do two things at once. The problem appears to be caused by a logjam of nerve messages. Faced with two almost simultaneous (同时的) tasks less than 300 milliseconds apart, the brain's ability to deal with the second one slows down. The neural (神经的) response to the second task was postponed until the response to the first was completed. This means that with e-mails, phone calls, text messages and online social media all competing for our attention, often against a background of television, radio or music, our brains can reach information overload. Scientists made the discovery after scanning the brains of volunteers attempting to multitask on a computer. The task was deliberately designed to involve the use of different senses and motor responses. Dr Rene Marois, one of the neuroscientists who carried out the experiment at Vanderbilt University in Nashville, Tennessee, said: "Our research offers neurological evidence that the brain cannot effectively do two things at once." The next step, the neuroscientists say, is finding out "why these areas cannot process two tasks at once." |
| 1. How many people can drive equally well while using a cell phone? |
| A. Nobody. B. Everybody. C. 2 in 100. D. 98 in 100. |
| 2. The researchers tried to find out the difference between _____ brain structures. |
| A. different supertaskers' B. supertaskers' and ordinary people's C. humans' and nonhuman primates' D. supertaskers' and nonhuman primates' |
| 3. We can infer from the article that the brain takes 300 milliseconds to _____. |
| A. make a neural response B. get ready for a response C. complete a task D. finish two tasks |
| 4. If we _____, our brains may reach information overload. |
| A. serf the Internet after listening to music B. use a cell phone against a background of television C. complete all kinds of tasks within the same day D. have lots of tasks queuing for responses |
| 5. From the dictionary explanations, choose one for the underlined word "motor" in Paragraph 5. |
| A. having an engine B. relating to vehicles with engines C. relating to nerves that make muscles move (control body movement) D. the part of a machine that makes it move |