题干

青霉素刚制造出来时,能杀死多种致病细菌,是人们治病的良药。但由于人们滥用青霉素,使得有些细菌不再受青霉素影响了。对这种现象的合理解释是(  )

A:细菌的适应能力特别强

B:能抵抗青霉索的细菌存活下来,且大量繁殖

C:青霉素的药效很不稳定

D:青霉素使细菌发生变异,细菌产生了抗药性

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答案(点此获取答案解析)

B

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    In 1971 a young man who grew up very poor was traveling across the country, trying to make a new start for himself. Along the way he had completely run out of(用光了...) money and was forced to spend the night in his car. This continued until one morning, after a week of sleeping in his car, he walked nervously into a restaurant and ordered a big breakfast.

    After eating his first good meal in weeks, he found himself lying to the waiter, telling him he had lost his wallet. The waiter, who was also the owner, walked behind the chair where the young man had been sitting. He bent down, and came up with a $20 bill that looked as if it had fallen on the floor and said, “Son, you must have dropped this,”the owner said. The young man couldn't believe his luck! He quickly paid for the breakfast, left a tip, bought gas with the change, and headed West.

    On the way out of town, he began to understand what the owner did. Maybe nobody dropped the money at all.“Maybe that fellow just knew I was in trouble and he helped me in a way that didn't embarrass(使尴尬)me. So I just made a promise to help other people if I can.”

    Later, he worked very hard and became a rich man. Now he lives near Kansas City. Each year he gives away thousands of dollars. He is known as the “Secret Santa” because at Christmas time each year, he personally hands money out to those on the street and at restaurants. Last year, he gave more than $50,000 away in Kansas City.