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发布日期:2021-03-13
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根茎是指延长横卧的根状地下茎。有明显的节和节间,节上有退化的鳞片叶,前端有有顶芽,旁有侧芽,向下常生有不定根。根吸收土壤小的水分和矿物质,而茎干暴露在光和大气中,在根和茎干之间存在物质的运输。
主根(axial root),亦称“初生根”。由胚根发育而成的根。主根具有强烈的向地性,可垂直向土层深处生长2-3米,一般栽培的灌木型茶树根系可深入1米以下的土层。
称为,汉语词语,拼音是chēng wéi,意思是指叫做。
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关于临终关怀正确的是()。
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一般认为,在记忆过程中包括三个连续阶段,他们是()、()和()。
()是税收制度和政策的中心环节,直接关系到国家财政收入和纳税人的负担。
请阅读 Passage 1,完成第 21~25小题。Passage 1These days,many large city buildings are equipped with their own air-conditioning systems.These systems help keep the buildings cool,but they can also damage the environment.Since they use a lot of electricity,for instance,they contribute indirectly to global warming.In addition,the water that flows through the systems is often cooled using chemicals called chlorofluorocarbons,or CFCs,that are believed to damage the Earth's ozone layer.Recently,though,a system has been built in the city of Toronto,Canada,that cools buildings with little damage to the environment. In the traditional air-conditioning systems found in most large buildings,water is pumped through the building in a continuous cycle.The water is first cooled to a temperature of 4℃ in machines called chillers.It is then sent to individual units that cool the air in each room.As the water flows through the building,it gradually becomes warmer.Finally,it reaches the roof ,where it is left to cool down naturally in a water tower.After that it is returned to the chillers,where the cycle begins again.Toronto lies on the shore of Lake Ontario,one of North America's Great Lakes,and the new system makes use of cold water taken from about 80 meters below the surface of the lake.At this depth,the water in the lake remains at 4℃ all year round.This is exactly the temperature to which the water in air-conditioning systems is cooled.However,the water from the lake is not pumped directly into the air-conditioning systems.Instead,it is used to cool the water that is already inside the air-conditioning systems.After that,the lake water is added to the city's ordinary water supply.Enwave,the company that developed this deep-lake cooling system,says that it uses 75 percent less energy than traditional air conditioning.And since no CFCs are used,no damage can be caused to the ozone layer.Not every city is located next to a large lake,but experts believe that systems like the one being used in Toronto could be built elsewhere by using other natural sources of cold water.What is one advantage of Enwave 's new system?
仙、佛、菩萨,有何分别?现在的玉皇大帝是否关圣帝君?他不过重忠义,为何位列观音大士之上?
一小儿红细胞2.5×1012/L,血红蛋白80g/L,该小儿可能是( )。
中国特色社会主义道路,中国特色社会主义理论体系,中国特色社会主义制度是党和人民九十多年奋斗、创造、积累的根本成就。
安全带使用3—5年即应报废。
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