很多同学说，英语学习是很难啃的骨头，而最难的关节是记忆单词，如何记忆英语单词？大家都会说，背。如何背？看着单词，花时间背。我发现，的确有很多同学是下定决心，不怕 辛苦，背...
一些英语基础较弱的同学经常为学不好英语而苦恼，找不到学习英语的有效途径。实际上，背诵是学好英语的重要方法之一，练好背功是很重要的。在背诵时要注意以下几个方面： 一、背单词...
Cells cannot remain alive outside certain limits of temperature and much narrower limits mark the boundaries of effective functioning. Enzyme systems of mammals and birds are most efficient only within a narrow range around 37C;a departure of a few...
Sleet is part of a persons daily activity cycle. There are several different stages of sleep, and they too occur in cycles. If you are an average sleeper, your sleep cycle is as follows. When you fist drift off into slumber, your eyes will roll abou...
Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in microns. One micron is a thousandth of a millimeter: a pinhead is about a millimeter across. Rod-shaped bacteria are u...
A folk culture is a small isolated, cohesive, conservative, nearly self-sufficient group that is homogeneous in custom and race with a strong family or clan structure and highly developed rituals. Order is maintained through sanctions based in the r...
46.Vision Human vision like that of other primates has evolved in an arboreal environment. In the dense complex world of a tropical forest, it is more important to see well that to develop an acute sense of smell. In the course of evolution members...
45.The source of Energy A summary of the physical and chemical nature of life must begin, not on the Earth, but in the Sun; in fact, at the Suns very center. It is here that is to be found the source of the energy that the Sun constantly pours out i...
44.Obtaining Fresh water from icebergs The concept of obtaining fresh water from icebergs that are towed to populated areas and arid regions of the world was once treated as a joke more appropriate to cartoons than real life. But now it is being con...
43.Statistics There were two widely divergent influences on the early development of statistical methods. Statistics had a mother who was dedicated to keeping orderly records of government units (states and statistics come from the same Latin root s...
