【正文】
Plants depend on nitrogen to stay alive. 植物依靠氮氣來生存。 ? 7) More than threefourths of the gas is nitrogen. ? 氣體中四分之三的氣體都是氮氣。 ? 8) People who travel to the mountains find it harder to breathe. ? 到山上旅行的人發(fā)現(xiàn)這里呼吸比較困難。 ? 9) Big cities are full of cars. 大城市里都是汽車。 ? 10) They are used for business and pleasure. 他們是用來商務(wù)和娛樂的。 ? 11) Something should be done about the use of cars in order to have cleaner air. ? 為了得到更清潔的空氣,應(yīng)該就汽車的使用問題采取措施。 ? 六、本單元重點知識講解: ? 1. The ship is made from waste materials. ? The Tshirt is made of cotton. ? 例如: ? ① The book is made of paper and paper is made from wood. ? ② The glass is made of glass and glass is made from SiO2. ? 2. The air that surrounds the earth is called the atmosphere. ? 包圍地球的空氣被稱為大氣。 ? be called 被稱為 ? 同義詞: be named ? 例如: ? The boy is called “Da Niu” by his classmates. ? The machine is called “Washing machine”. ?