人教版高中英语课件：unit 13 reading.ppt

pre-readingpre-reading structure of the passagestructure of the passage 1 minute to skim the passage, focusing on the titles (title and subtitles)in the text and then fill in the chart below. you do not need to read the whole text. the properties of water chemical structure salinity density heat capacity ocean motion skim and find out the topic sentences task one topic sentence of heat capacity: paragraph: _ sentence: topic sentence of density: paragraph: _ sentence: 4 4 the density of pure water is 1,000 kg/m3, meaning that the density of pure water is 1,000 kg/m3, meaning that one cubic one cubic metremetre of water weighs one thousand of water weighs one thousand kilogrammeskilogrammes. . 5 5 heat capacity is the mount of energy it takes to raise the heat capacity is the mount of energy it takes to raise the temperature of a substance by one degree centigrade.temperature of a substance by one degree centigrade. topic sentence of ocean motion: paragraph: _ sentence: 6 6 since changes in salinity and temperature affect waters since changes in salinity and temperature affect waters density, the water in the ocean is always moving. density, the water in the ocean is always moving. topic sentence of the text: paragraph: _ sentence: topic sentence of salinity: paragraph: _ sentence: topic sentence of chemical structure: paragraph: _ sentence: 7 3 3 2 learning about the properties of water helps us learning about the properties of water helps us understand life on our planet.understand life on our planet. the chemical structure of water makes it an the chemical structure of water makes it an excellent medium for life.excellent medium for life. the salinity of the earths oceans is about thirty-five the salinity of the earths oceans is about thirty-five parts per thousand, meaning that there are about parts per thousand, meaning that there are about thirty-five thirty-five grammesgrammes of dissolved solids and gases in of dissolved solids and gases in one one kilogrammekilogramme of water. of water. scan and find out the main idea. task two para 1: para 2: para 3: para 4: para 5: para 6: the properties of water make the ocean a great place to live in. the chemical structure of water makes it an excellent medium for life. the salinity of sea water effects both its weight and freezing point. marine animals and plants take advantage of the density of sea water. the heat capacity of water keeps the temperature of the ocean steady , making it a safe and comfortable habitat. para 6: ocean motion adds energy to the marine ecosystems and moves nutrients around. scan and fill in the form: propertywhat is it? what is it good for? chemical structure density heat capacity ocean motion task three chemical structure: good: because water is polar,it can break down nutrients quickly. they can quickly become available to other living creatures. the water molecule is made up of two hydrogen atoms and one oxygen atom. the water molecule is polar-it has a slightly negative and a slightly positive end. density: density is the relationship between mass and volume. good: marine animals and plants take advantage of the density of water . it helps small creatures to float. because the density of water decreases when it freezes,the ocean never freezes totally. heat capacity: heat capacity is the amount of energy it takes to raise the temperature of a substance one degree centigrade. good: the heat capacity of water keeps the oceans at a steady temperature ,which makes it a good place to live for creatures that are sensitive to sudden changes in temperature . the water in the oceans also keeps the temperature of earth steady. ocean motion: dense water sinks and less dense water is pushed to the surface.so the water in the ocean is always moving. good: the circulation adds energy to marine ecosystem and moves nutrients around. task four true or false true(t) or false(f) 1.life on the earth began on the land some three billion years ago. 2. life in the ocean ranges from tiny plankton to giant whales. 3. the water molecule is made up of two oxygen atoms and one hydrogen atoms. 4. because water is polar,it can not break down nutrients quickly. 5. water is solid at room temperature. 6. sea water is similar to pure water in many ways,but is heavier and has a higher freezing point. 7.a substance with higher density will float on a substance with lower density. 8.because the density increases when the water freezes,the ocean never freezes. 9. the heat capacity makes the ocean a safe and comfortable habitat to live in. words competition example: otma quienu sdlio oasbrb cgrnetidea rupe nhroygde yoxgen assm fatol atom unique solid absorb centigrade pure hydrogen oxygen mass float range fromto range between and 海洋里的生物从微小的浮游生物到巨大的动物，如 鲨鱼和鲸鱼，都无所不包。 1.their ages range from 12to 25. 2.prices range between 30 yuan and 50 yuan 1.life in the oceans ranges from the tiniest plankton all the way up to giants like shakes and whales. 从到之间变化 2. the nutrients in whatever falls into the ocean quickly became available to other living things. 通过任何渠道进入海洋的营养物质都能很快被 其他生物所利用. whatever引导名词性从句,相当于 anything that 1.it is not wise to give children whatever they want. (宾语从句) 2.whatever do is for your good.(主语从句) 3.take whatever you want.(宾语从句) 注意:whatever 引导名词性从句时,不能用no matter what代替 拓展：引导状语从句时， no matter what=whatever no matter who=whoever no matter where= wherever no matter when=whenever no matter how=however 1.不管发生什么事，我们都决心完成任务。 whatever happens,we are determined to complete the task. =no matter what happens, 2.无论你什么时候来，我们都欢迎。 3.无论谁触犯了法律，他最终都会受到惩罚。 no matter when you come ,you are welcome. =whenever you come, no matter who breaks law,he will be punished in time. =whoever breaks law, 3.even though the pure water is what gives sea water its main properties,the salinity of sea water affects both its weight and freezing point. 尽管是纯水赋予了海水的主要特征,然而海水的 盐度却影响了它的重量和冰点. what gives sea=the thing that gives sea 为表语从句 她不是她以前的样子了. she is not what she used to be. 4.marine animals and plants take advantage of the density of water. 海洋动物和植物利用了水的密度的特性. take advantage of 1.i took advantage of the fine weather to play tennis.(利用机会) 2.he often took advantage of her trustfulness. (利用别人的弱点或处境) have an advantage over 在某方面比较有利 1.you see,you have an advantage over me. you can make a dress. 5.water can absorb and give off a lot of heat without big changes in temperature, thus creating a stable environment. 海水可以吸收或释放出大量的热量而其温度不会 变化很大,因此,能创造一个稳定的环境. absorb 吸收 black cloth absorbs heat. be absorbed in.专心于 i was absorbed in a book and didnt hear your call. give off 释放 the flowers give off a sweet fragrance. stable 稳定的 a stable job his character is very stable. 6.most animals are sensitive to large or sudden changes in temperature. 大多数动植物对于温度的巨变或突变