6．4 Exercises练习
Ⅰ．Sentence translation．
1．A magnet＇s poles always points north and south．
2．The craters on the moon looks like deep pits．
3．The major problem in“fabrication”is the control of contamination and foreign material．
4．We will be tracing slow acquisition of knowledge about material world by scientists in many different cultures．
5．The whale，swimming like a fish，is a mammal．
6．Since ancient times，various ideas have been suggested on the nature of dreams．
7．Handle with care．
8．The experiment should succeed and would if no mistake occurred．
9．The best clock cannot but entail a certain error．
10．These side effects can be overcome by slight adjustment．
11．There are many kinds of bacteria which vary in shapes and sizes．
12．The brain is the center of our nerve system．
13．The present process of making steel from iron is only about 100 years old．
Ⅱ．Passage translation．
Neuro-computer architecture is modeled on current understanding of the way the human brain encodes and processes information．Nodes in a neural network，called processing elements，model individual nerve cells，or neurons，in the human nervous system．In the brain，each neuron receives electrochemical impulses from thousands of other neurons．If the sum of the signals received is strong enough，the neuron sends it onto another nerve cell or to a muscle or organ．Laboratory scientists are now trying to determine how the organic network of nerve cells is arranged and what happens within a neuron when learning takes place．
Neural network simulation software lets developers work with some of the dozens or so best-known theories of brain organization and learning．They can experiment with processing elements and the strengths of signals between the elements．The brain is a massively parallel processor，working on many inputs at once; neuron-computers are also inherently parallel．But most currently available products are software packages of add-in boards that simulate neural networks in conventional serial computers．