根据第一段第一行“Air is not just one gas,it is a mixture of different gases,空气不仅仅是一种气体,它是不同气体的一个混合 ”可知答案为C,空气是不同气体的一个混合;A项:空气只是一种气体;B项:空气是两或三种气体的混合,第二段第一句提到“空气中主要有四种气体”故B错误;D项:空气不存在。2、...
5. 选择题: 1. C. keeps 空气使它们高高地飞翔。 2. B. or 空气没有颜色或形状。 3. C. was, is 这里的空气过去很干净,但现在有时很脏。 4. A. fresh 我们应该打开窗户保持教室空气新鲜。 5. B. make 不要扔石头,那会使妈妈生气。反馈 收藏 ...
Air pollution occurs when gases, dust particles, fumes (smoke), or odors are introduced into the atmosphere in a way that makes it harmful to humans, animals, and plants. Air pollution results in the air being dirty (contaminated, unclean, and often toxic). The Earth is surrounded by a b...
Chemistry is the study of matter and how it changes. Matter is everything that has mass and takes up space, like the air we breathe, the water we drink, and the objects we use every day. Chemistry helps us understand what things are made of and how they interact with each other. For...
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 l...
What is air? It has no colour, smell or taste. We can feel it. When it moves, it becomes wind. Air is important to the world. People need it. Animals need it. Plants need it too. So we must keep the air clean and fresh. Don't smoke. Don't drive to school or work if you...
What ___ the air dirty? ( ) A. make B. makes C. is making D. NO 相关知识点: 试题来源: 解析 [答案]B [解析]句意:什么使空气变脏?该句时态为一般现在时,疑问词what(什么)做主语时,谓语动词应用第三人称单数形式,make的第三人称单数是makes,故选B。反馈...
have recently gained recognition as pollutants by some scientists. Others recognize the gas as being essential to life and therefore incapable of being classed as a pollutant.参考:Air pollution is a chemical physical (e.g. particulate matter)or biological agent that modifies the natural ...
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。（...
and thick blankets can now dry much quicker. Additionally, the Easy-to-ironAIR TURBOfunction is suitable for delicate and synthetic fabric clothing. There's no need to hang and wait for clothes to dry anymore – simply iron them right out of the washer, as AIR TURBO rem...