What is air made of? The Earth's Atmosphere: The Earth's atmosphere is a layer--or series of layers--of gasses that envelope the Earth's surface. The atmosphere is usually divided into the troposphere, the stratosphere, the mesosphere, the thermosphere, and the exosphere. ...
It is a mixture of different gases可知正确答案.故答案为C.(4).【答案】A【解析】由原文第三段的If 1000 dots can represent the air, then 776 of them are nitrogen, 210 are oxygen, 11 are argon可知正确答案.故答案为A. 结果一 题目 2.阅读理解。What is air? Air is not just one gas....
The particle view of matter is one of the core ideas of science that is involved in explaining myriad science phenomena. From early on, pupils explain everyday phenomena such as air pollution using their intuitive ideas and models of matter. However, research about primary school children's ...
So we must keep the air clean and fresh. Don't smoke. Don't drive to school or work if you can take a bus or the underground. Of course, walking or riding a bike is the best. We can also plant trees or other plants to keep the air clean.阅读短文,选择正确的答案。( )1.___...
There is no chemical formula for air. The air that we breathe is a mixture of several gasses, including oxygen (O2), nitrogen (N2) and carbon dioxide...Become a member and unlock all Study Answers Start today. Try it now Create an account Ask a question Our experts can answer your...
The Earth is surrounded by a blanket of air (made up of various gases) called the atmosphere. The atmosphere helps protect the Earth and allows life to exist. Without it, we would be burned by the intense heat of the sun during the day or frozen by the low temperatures at night. ...
分析句子可知,What the plants pump through the air(植物在空气中所释放出的东西)是主语从句,a mixture of chemicals(一种化学混合物)是表语,known as volatile organic compounds(称为挥发性有机化合物),VOCs for short(简称VOCs)是volatile organic compounds的同位语。故翻译为:植物在空气中所释放出的是一种被...
一、由感叹词what引导的感叹句。1.① What+a/an+（形容词）+单数可数名词+主语+谓语！② What+名词词组+主语+谓语！如: What a fine day it is!2. What+(形容词）+可数名词复数或不可数名词+主语+谓语!如: What kind women they are!What nice music it is!二、由How引导的感叹句。（...
【分析】A is to B what C is to D这是一个固定用语,是一个表修辞类比的句式,意思是“A之于B正如C之于D”。句意:空气对于人类来说正如水对于鱼一样。选B。 【点评】在这一固定用语中,what作连接代词,用来比较说明两种事物相同或相似的关系,起比喻作用,相当于连接词as,意为“正如、好比、就象……一...
An AQI value of 50 or below is classified as "good air quality," according to health experts. Once the AQI index reaches 100 or above is when the air quality is considered unhealthy and may impact certain groups of people.The Air Quality Index displayed on AirNow.gov shows the ...