①Chemistry is everywhere in our daily life. Sometimes it's easy to see. At other times, it can be very hard to see the everyday chemistry at work, but nearly everything you touch has some chemicals (化学物质) in it.
②Chemistry helps to make products for use. Something as simple as toothpaste has at least three chemicals that keep your teeth clean. Other things in your daily life are created by chemistry, such as hair products and soap. Without chemistry, we would never have known that we need soap to get the oil out of clothes.
③Chemistry also helps us understand the world around us. Thanks to chemistry, we know bleach (漂白剂) can't be mixed with vinegar (醋), because the mixture can produce harmful gas.
④Chemistry plays a big role in food preparation. Cooking food causes it to go through a chemical change. That is the reason why cooked food often tastes different from uncooked food. Too much or too little of any chemical material makes a difference to the result of baking (烘焙). For example, the cake can be too soft or too hard.
⑤Chemistry isn't something that just lives in a laboratory; it's something that you meet hundreds of times in life. Knowing how chemistry works will give you a greater understanding of the life.
31. What can the chemistry in soap help us?
A. To clean the teeth. B. To make the teeth strong.
C. To clean the oil off clothes. D. To make the clothes new.
32. From the third paragraph, we know that ________.
A. we can mix bleach with vinegar B. the mixture can produce useful gas
C. we can't mix bleach with vinegar D. chemistry can't help us make products
33. The fourth paragraph mainly tells us that ________.
A. cooked food is much better than uncooked food
B. chemistry plays a big role in food preparation
C. there are no chemical changes while we are cooking
D. the cake can't be too soft or too hard with chemistry
34. Which of the following shows the structure (结构) of the passage? (①=Paragraph 1)
A. B. C. D.
35. What's the main idea of the passage?
A. Chemistry and food. B. Chemistry around the world.
C. Chemistry and products. D. Chemistry in everyday life.
这是一篇说明文，文章主要讲述化学物质无处不在；讲述化学物质的用途；知道化学的原理能够更好地理解生活。
31.C【解析】细节理解题。根据第二段“Without chemistry, we would never have known that we need soap to get the oil out of clothes.”可知肥皂里的化学物质可以帮助我们清洗衣服上的油渍。故选C。
32.C【解析】细节理解题。根据第三段“Thanks to chemistry, we know bleach (漂白剂) can't be mixed with vinegar (醋), because the mixture can produce harmful gas”可知漂白剂和醋不能混合，因为会产生有害的气体。故选C。
33.B【解析】段落大意题。根据第四段第一句“Chemistry plays a big role in food preparation”可知这一段主要讲述化学物质在食物准备上的重要作用。故选B。
34.A【解析】文章结构题。文章的第一段主要讲述化学物质无处不在。第二段到第四段讲述化学物质的用途，第五段总结化学物质是生活中常见的东西，知道化学的原理能够更好地理解生活。故选A。
35.D【解析】主旨大意题。文章主要讲述化学物质在日常生活中的用途和作用。可概括为Chemistry in everyday life。故选D。