题干

 除去下列物质中的少量杂质,所选试剂及操作方法都正确的是(  )

 选项

 物质(括号内为杂质)

 试剂

 操作方法

 A

 CaCO3(CaO)

﹣﹣

 高温煅烧

 B

 KOH溶液(K2CO3

 适量Ca(OH)2溶液

 滴加试剂、过滤

 C

 Ag(Fe)

 适量CuSO4溶液

 滴加试剂、过滤

 D

 CO2(CO)

 足量NaOH溶液

 洗气、干燥

A:A

B:B

C:C

D:D

上一题 下一题 0.0难度 选择题 更新时间:2011-04-02 03:10:51

答案(点此获取答案解析)

B

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    One year my children came home from school asking where we were going on your summer vacation. It seemed that all the other kids were1 where they were spending the summer. I couldn't 2to take them anywhere but I didn't want to tell them that so I just said, “It's a surprise!” They were 3. That bought me a little more 4.

    I called several amusement 5to see if there was a half-price event during the summer but no such 6. I tried everything, with no success, so I called some of the other moms to find that most were in the same7that I was. We decided to8 something fun for our kids to do. We had a meeting, all five of us, and9 what is now called a “playcation”.

    One mother was a  10, so on Mondays the kids would all go to her house. They would play games using plants and11. They also planted vegetables and12 them grow over the summer.

    Another mother had Bible 13 on Tuesdays. She asked some questions about Bible. The kid who answered  14got a penny, which they all turned in at the end to buy their goodie bags(礼品袋).

    At our house on Wednesdays, I made an outdoor 15training with my spare tires. The kids also walked a balance beam and raced through large cardboard boxes taped together.

    On 16they had arts and crafts across the street. Fridays were17by a wonderful single dad with a metal detector(金属探测器)who took everyone out treasure18 .

    The summer was a big19 . Okay, it wasn't Disney World,20 the kids didn't miss anything. My son actually asked me, “Can we do this again next year?”