题干

下列有关实验的描述,正确的是(  )

A:镁在空气中燃烧,火星四射,生存黑色固体

B:配制一定质量分数的氯化钠溶液,一般步骤为:计算、称量、溶解、转移

C:将固体氢氧化钠溶于水中,溶液的温度显著降低

D:将棉花点燃,闻到一股烧焦羽毛的气味

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答案(点此获取答案解析)

B

同类题1

完形填空

    I do not know why I came to the decision to become a loser, but I know I made the choice at a young age. Sometime in the middle of fourth grade, I stopped 1. By the time I was in seventh grade, I was your2degenerate (颓废): lazy, rebellious, and disrespectful. I had lost all social 3 I terminally (不可救药的) followed, what was fashionable.

    Not long after that, I dropped out of school and 4 my downward spiral. Hard physical labor was the5for the choices I made as an adolescent. At the age of twenty-one, I was6 lost and using drugs as a way to deal with the fact that I was uneducated and7 in a dead-end job carrying roof materials up a ladder all day.

    But now I believe in do-overs, in the8 to do it all again. And I believe that do-overs can be made at any point in your life, if you have the right 9 Mine came from a10source.

    It was September 21, 2002, when my son Blake was born. It's funny that after a life of 11responsibility, now I was in charge of something so 12Over the years, as I grew into the title of Dad, I began to learn something about myself13 Blake and I were both learning to walk, talk, work, and play for the first time. I began my do-over.

    It took me almost three years to learn 14to read. I started with my son's books. Over and over, I practiced reading books to him15 I remembered all the words in every one of them. I began to wonder if it was possible for me to go back to school. I knew I wanted to be a good role model,16 after a year-and-a-half and a lot of hard work, I passed my GED test on my son's fourth birthday. This may not sound like 17and I am not trying to get praise for doing something that should have been done in the first place, but all things considered it was one of the18days in my life. Today, I am a full-time college student, studying to become a sociologist.

    Growing up, I19 heard these great turn-around stories of triumph over shortcomings. But I never thought they applied to me. Now I believe it is a (an)20anyone can make: To do it all over again.

同类题2

阅读短文, 从每题所给出的(A、B、C、D)四个选项中选出最佳选项。

Michael Rossi is the Internet favorite Dad right now.

Mr. Rossi, a father from Philadelphia, recently took his kids, Jack and Victoria, to Boston for three days during the school term. But Rydal Elementary School, one of the oldest schools in Boston, doesn't accept family holidays as an excuse for their absence and give them a warming notice. So Mr. Rossi wrote a letter to the school, which has been shared by thousands of parents online.

   Dear Mrs. Marbyry,

   While I am thankful for your concern for our children and the best education our kids receive from you, I can promise you they’ve learned as much in the three days we were in Boston as they would in a whole year in school.

   Although they missed an important test, they learned about something more important for them, especially for their future.

   They experienced first –hand the love and support form thousands of other people with a common goal. At the marathon(马拉松) , which is known as the most difficult one in the world, they watched runners with disabilities work together to collect money for children in poor areas.

In addition, our children walked the Freedom Trail, visited the site of the Boston Tea Party and the graves of several great pioneers of America. These are thing they WILL learn in school a year or more from now.

   We truly love our school and teachers. But I wouldn't hesitate (犹豫) to pull them out of school again for an experience like the one they had this time.

   Thank you for your time.

Sincerely,

Michael Rossi