题目内容
羊毛属于蛋白质纤维，它是α-氨基酸的天然聚合物, 其中含有大量的酸性,碱性或其他极性侧链。它具有两性，氨基使羊毛具有碱性，其表现为羊毛可以吸酸；羧基可使羊毛具有酸性，其表现为羊毛可以吸碱。
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羊毛在等电点时，羊毛电离的氨基和羧基数目相等，纤维为电中性。
弱酸性染料染羊毛时，可用醋酸调pH值。
Task 2Listen to the monologue again and fill in the missing words or phrases according to what you hear.[音频]Do you have a 1in your house? What about a 2 for your car? Both of these can help you make 3. Many people who are feeling the pinch are 4what's been called the “5”.Perhaps the 6of a company in this field is Airbnb , an American web business which allows you to 7your spare room to 8. It says it operates in 34,000 cities and it has 800,000 listings of rooms and 9. They seem to have 10the market!
Task 1Listen to the dialogue about bike sharing and decide whether the following statements are true (T) or false (F). The following sentences may help you.[音频]Mike rides a bike to school because of a traffic jam on Monday. ( )
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