题干

已知实验室可用加热氯酸钾和二氧化锰的混合物制氧气,其中二氧化锰在反应中起加快氯酸钾分解的作用,某同学在用加热氯酸钾制氧气的实验中忘记了加二氧化锰,其结果是( )

A:反应较慢,但产生氧气总量不变

B:反应较慢,但产生氧气总量减少

C:反应正常,产生氧气总量不变

D:反应正常,产生氧气总量减少

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答案(点此获取答案解析)

A

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B

    “Can I take your order?”Night after night.I had to say this as l worked in my family's restaurant.My father was a fantastic cook.He wanted me to cook with him.but I didn't like cooking.Because of the restaurant, my father was always busy.He never had time to play soccer with me.

    During my high school and college years,I worked with my family at night.But I always avoided the kitchen.I couldn't wait to graduate (毕业),so I could move away from the family business(生意).Several days before my graduation day, my father and I started looking at new cars.Finally, we found the right car.I was sure that my father would give it to me as my graduation gift.

    On my graduation day, my father gave me a book as a gift.It was his old cookbook.I was so angry that I gave it back to him and ran out of the house.I soon moved away and started my own business.Although I often saw my father during holidays,we never talked about the graduation gift.Then one day, I got a call that my father was sick.I went to see him because l was very worried.

    That night, I looked through my father's books and saw the cookbook that he had given me years before.I carefully opened the cookbook and went through it.Then I found something that made me cry.It was a check(支票)for$30,000 dated(注有日期)the day of my graduation.And the price of the car my father and I chose all those years ago was $30,000.