【正文】 the concentration of acetylcholine in the synaptic cleft is very low. Low synaptic concentrations of acetylcholine can be maintained via a hydrolysis reaction catalyzed by the enzyme acetylcholinesterase. This enzyme hydrolyzes acetylcholine into acetic acid and choline. If acetylcholinesterase activity is inhibited, the synaptic concentration of acetylcholine will remain higher than normal. If this inhibition is irreversible, as in the case of exposure to many nerve gases and some pesticides, sweating, bronchial constriction, convulsions, paralysis, and possibly death can occur. Although irreversible inhibition is dangerous, beneficial effects may be derived from transient (reversible) inhibition. Drugs that inhibit acetylcholinesterase in a reversible manner have been shown to improve memory in some people with Alzheimer39。s important to do regular exercises. There are many easy and useful sports for us to do such as going for a walk, jogging, swimming, dancing and so on. Third, it39。m satisfied with it. I think my home is cozy and I like my home. My Favorite Transportation Means 我最喜歡的交通方式 Everybody has his favourite transportation means. For me I like cycling most. I think I can benefit a lot from it. First , cycling is a good exercise. I bee stronger and healthier by cycling everyday. Second It39。m free. I think there are many advantages for us to swim. It can lose my weight and be graceful in form. It is good for keeping fit and refreshing. I like swimming especially in summer because it is very hot in Chongqing. When I jump into water. I feel cool and relaxed. Swimming is an easy and popular sport. There are many small swimming pools spotted among the residential areas now. I can go swimming whenever as I like. Health and Eating Habit 健康與飲食習(xí)慣 It39。s a big burden for them. Therefore our government and society should establish a multilevel oldage insurance system and take all kinds of measures to make the elderly people live a happy and healthy life in their old age. My English Study 我的英語(yǔ)學(xué)習(xí) English is being more and more important in our work and life because it is widely used in the world. So a lot of people are trying their best to learn English well. However, I met many difficulties in learning it. There are too many grammar rules to remember. It39。 the harnessing of accidents that occurred during the process of painting。 and the attempt to transfer pure emotion directly onto the canvas. The movement had an inestimable influence on the many varieties of work that followed it, especially in the way its proponents used color and materials. Its essential energy transmitted an enduring excitement to the American art scene. Science and technology is quite a broad category, and it covers everything from studying the stars and the plas to studying molecules and viruses. Beginning with the Greeks and Hipparchus, continuing through Ptolemy, Copernicus and Galileo, and today with our work on the International Space Station, man continues to learn more and more about the heavens. From here, we look inward to biochemistry and biology. To truly understand biochemistry, scientists study and see the unseen by studying the chemistry of biological processes. This science, along with biophysics, aims to bring a better understanding of how bodies work – from how we turn food into energy to how nerve impulses transmit. analytic geometry, branch of geometry in which points are represented with respect to a coordinate system, such as Cartesian coordinates, and in which the approach to geometric problems is primarily algebraic. Its most mon application is in the representation of equations involving two or three variables as curves in two or three dimensions or surfaces in three dimensions. For example, the linear equation ax+by+c=0 represents a straight line in thexyplane, and the linear equation ax+by+cz+d=0 represents a plane in space, where a, b, c, and dare constant numbers (coefficients). In this way a geometric problem can be translated into an algebraic problem and the methods of algebra brought to bear on its solution. Conversely, the solution of a problem in algebra, such as finding the roots of an equation or system of equations, can be estimated or sometimes given exactly by geometric means, ., plotting curves and surfaces and determining points of intersection. In plane analytic geometry a line is frequently described in terms of its slope, which expresses its inclination to the coordinate axes。m sure I39。s bad to eat too much fat and some junk food. These things make us overweight and cause some illness. It39。s my duty to pick up my daughter in the afternoon. My wife is good at