The more time scientists spend designing computers, the more they wonder at human brain. Tasks that puzzle the most advanced supercomputer—recognizing a face, reading a handwritten note —are child's play. Most important, unlike any ordinary computer, the brain can learn from its mistakes. Researchers have tried for years to program computers to imitate the brain's abilities, but without success. Now a growing number of designers believe they have the answer: if a computer is to work more like a person and less like an overgrown calculator it must be built more like a brain, which distributes information across a vast interconnected web of nerve cells or neurons. Ordinary computers work by following a chainlike sequence of detailed instructions. Although very fast, their processors can perform only one task at a time. This approach works best in solving problems that can be broken down into simpler logical pieces. The processors in a neural-network computer, by contrast, form a network much like the nerve cells in the brain. Since these artificial(人造的)neurons are interconnected, they can share information and perform tasks at the same time. This two-dimensional approach works best at recognizing patterns. Instead of programming a neural-network computer to make decisions, its maker trains it to recognize patterns in any solution to a problem by repeatedly feeding examples to the machine. Neural networks come in all shapes and sizes. Until now most existed as software simulations(模拟品)because redesigning computer chips took a lot of time and money. By experimenting with different approaches through software rather than hardware, scientists have been able to avoid costly mistakes.

单选题 It can be inferred from the first paragraph that a computer______.

【正确答案】 B

【答案解析】解析：逻辑推理题。从第一段，Tasks that puzzle the most advanced supercomputer—recognizing a face，reading a handwritten note，可以看出认出人脸和读出手写的便条都是最高级的计算机做不了的事情，所以A和D都是错误的。从Most important，unlike any ordinary computer，the brain can learn from its mistakes可以得知，电脑是不能像人脑一样从自己的错误中总结经验教训的，所以B是正确的。从第二段开头这句，Ordinary computers work by following a chainlike sequence of detailed instructions，可以得知，电脑是可以遵循详细的指令的，所以C是错误的。

单选题 Which of the following is NOT true about an ordinary computer?

【正确答案】 D

【答案解析】解析：从第二段开头这句，Ordinary computers work by following a chainlike sequence of detailed instructions(电脑的工作原理就是遵循一系列详细的指令)，可知选项A是正确的表达。从第二句，Although very fast，their processors can perform only one task at a time，可知B也是正确的表达。从第三句，This approach works best in solving problems that can be broken down into simpler logical pieces(在处理能够破解为更简单的逻辑编码的问题时，效果最好)，可知选项C也是正确的表达。另外第三段第一句Instead of programming a neural-network computer to make decisions，its maker trains it to…中的instead of就已经表明了没有给电脑编程去让它做决定，所以选项D是错误的表达。

单选题 The main feature of a neural-network computer is that______.

【正确答案】 A

【答案解析】解析：本题问到神经网络计算机的主要特点，从第二段这句The processors in a neural-network computer，by contrast，form a network much like the nerve cells in the brain可以看出，神经网络计算机的处理器能够形成跟大脑神经细胞很相似的网络，也就是指interconnected web of neurons(互相交错的神经网)，这正是这种计算机不同于普通计算机最显著的特点。A为正确选项。

单选题 The expression "this two-dimensional approach" in the second paragraph refers to______.

单选题 Scientists use software rather than hardware in their experiments because______.

【正确答案】 B

【答案解析】解析：细节判断题。从最后一句By experimenting with different approaches through software rather than hardware，scientists have been able to avoid costly mistakes可以得知，用软件能够避免一些会导致重大损失的错误。costly，“昂贵的，代价高的”，avoid costly mistakes也就是指能够节约钱和时间，而不是避免所有错误(故选项C错误)，答案选B。