题干

室温时,CaCO3在水中的溶解平街曲线如图所示。已知25℃其浓度积为2.8×10-9mol2/L2,下列说法不正确的是(  )

A:x数值为2×10-5

B:c点时有碳酸钙沉淀生成

C:加入蒸馏水可使溶液由d 点变到a点

D:b点与d对应的的溶度积相等

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答案(点此获取答案解析)

C

同类题1

完形填空

    What would you do if you had $5, but were limited to two hours to make as much money as possible? Buy a lottery ticket. While this is the most 1suggestion from people, it means a significant risk in return for a 2chance.

    Tina Selling, who invented the3for her students of Stanford University, has a 4story to tell.

    Selling gave each of the fourteen teams a sealed envelope that contains five dollars of “seed funding”. They were5to spend as much time planning, but once they had6the envelop they then had two hours to make as much money as possible. The next week, each team were to7their project in a three-minute presentation.

    It8that most of the 14 teams didn't use the five dollars9 They realized that focusing on the10actually limited the problem way too tightly. They understood that five dollars is essentially11and decided to reinterpret the problem more12what can be done if 13with absolutely nothing?

    The average14on the five dollar investment was 4,000 percent! So what did they 15do?

    One team started a stand on campus to check bike tire16for free and charged $1to refill tires. Another team made17at busy restaurants and then sold each of them for up to twenty dollars to customers who didn't want to18inline. The team who made the greatest 19sold their presentation time to a company that wanted to employ them to advertise. They 20a good business for that company in the three minutes' presentation and brought in $ 650,000.

同类题5

阅读下面短文,掌握其大意,然后从每题所给的A、B、C、D四个选项中选出一个最佳选项。   

    "Double 11" is coming. Many people say it's Bachelor's Day(光棍节) because it's named after the 1 November 11th. For most young singles, it's such a special day that they usually 2  lots of shopping online to celebrate themselves. They are happy because they are free.

    Whenever the day comes, I think of my parents. I once doubted whether there was 3 between my parents. Every day they were busy trying to make money for my brother and me. They never act 4 the romantic ways that I read in books or see on TV. In their opinion, "I love you" is too  5 for them to say. Sending each other flowers on Valentine's Day is  6 more impossible.

    One day, mom was sewing(缝纫) a quilt. I silently sat down beside her. "Mom, I have a question to ask you. Is there love between you and dad?" Mom stopped working and raised her head with  7 in her eyes. She never expected that I would ask her such a question. She didn't answer at once.

    I was worried because I thought I had hurt her and didn't know 8  to do. She thought for some time and said, "Look at this thread(线). Sometimes it appears, but most of it disappears in the quilt. The thread really makes the quilt strong. If life is a quilt, then the love should be thread. It can hardly be seen 9  or anytime, but it's really  10 . Love is inside."

    I couldn't understand her  11 the next spring, when Dad suddenly got sick seriously. Mom had to stay with him in the hospital for a month. When they returned, I read "love" in their hearts. After that, every day in the evening, mom  12 dad walk slowly on the country road. How    13  I was to see that!

    Once I thought love meant flowers, gifts and sweet  14. But from this experience, I know life a lot  15. Love is life. It is inside, making life strong and warm.