编辑点评: 研习GRE作文考试的优秀范文不仅可以学到有用的词汇和句子,更能从中学习逻辑的构建方式和作文框架的结构等内容,这里为大家提供GRE的范文,希望对同学们的备考有所帮助。
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 degrees from this value seriously impairs their functioning. Even though cells can survive wider fluctuations the integrated actions of bodily systems are impaired. Other animals have a wider tolerance for changes of bodily temperature.
For centuries it has been recognized that mammals and birds differ from other animals in the way they regulate body temperature. Ways of characterizing the difference have become more accurate and meaningful over time, but popular terminology still reflects the old division into warm-blooded and cold-blooded species; warm-blooded included mammals and birds whereas all other creatures were considered cold- blooded.
As more species were studied, it became evident that this classification was inadequate. A fence lizard or a desert iguana-each cold-blooded----usually has a body temperature only a degree or two below that of humans and so is not cold. Therefore the next distinction was made between animals that maintain a constant body temperature, called home0therms, and those whose body temperature varies with their environments, called poikilotherms. But this classification also proved inadequate, because among mammals there are many that vary their body temperatures during hibernation.
Furthermore, many invertebrates that live in the depths of the ocean never experience change in the depths of the ocean never experience change in the chill of the deep water, and their body temperatures remain constant.
全优课堂2017届高考总复习当堂过关微测:选修6 unit 4《Global warming》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修3 unit 5《Canada
全优课堂2017届高考总复习当堂过关微测:必修4 unit 2《Working the land》(新人教版含答案)
2017届高考英语一轮复习《全优课堂》写作技能步步高写作层级特训:要诀4.2.满分作文登场(新人教版含答案)
2017届高考英语一轮复习《全优课堂》写作技能步步高写作层级特训:要诀3.5.高级句式添彩(新人教版含答案)
2017届高考英语一轮复习《全优课堂》写作技能步步高写作层级特训:要诀4.5.满分作文登场.询问信(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修4 unit 4《Body Language》(新人教版含答案)
2017届高考英语一轮复习《全优课堂》写作技能步步高写作层级特训:要诀4.3.满分作文登场(新人教版含答案)
2017届高考英语一轮复习《全优课堂》写作技能步步高写作层级特训:要诀3.2.高级句式添彩(新人教版含答案)
2017届高考英语一轮复习《全优课堂》写作技能步步高写作层级特训:要诀2.1 亮点词汇增色(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:选修6 unit 2《Poems》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修1 unit 1《Friendship》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修2 unit 5《Music》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修4 unit 5《Theme parks》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修5 unit 2《The United Kingdom》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修4 unit 1《Women of achievement》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修5 unit 5《First aid》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修1 unit 4《Earthquakes》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修3 unit 3《The Million Pound Bank-Note》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修3 unit 1《Festivals around the world》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修1 unit 5《Nelson Mandela-a modern hero》(新人教版含答案)
2017届高考英语一轮复习《全优课堂》写作技能步步高写作层级特训:要诀1 基本句型护航(新人教版含答案)
2017届高考英语一轮复习《全优课堂》写作技能步步高写作层级特训:要诀3.1.高级句式添彩(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修2 unit 2《The Olympic Games》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修5 unit 3《Life in the future》(新人教版含答案)
2017届高考英语一轮复习《全优课堂》写作技能步步高写作层级特训:要诀3.4.高级句式添彩(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修1 unit 2《English around the world》(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:选修6 unit 3《A healthy life》(新人教版含答案)
2017届高考英语一轮复习《全优课堂》写作技能步步高写作层级特训:要诀2.2 亮点词汇增色(新人教版含答案)
全优课堂2017届高考总复习当堂过关微测:必修5 unit 4《Making the news》(新人教版含答案)
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