题干

2012年6月16日18点37分21秒,神舟九号载人飞船发射成功,与天宫一号目标飞行器进行首次载人空间交会手控对接,使中国的探月工程又迈出重要的一步.据预测,月球的土壤中吸附着数百万吨的氦23He,可作为未来核聚变的重要原料之一.对23He原子的叙述不正确的是(   )

A:质量数是3

B:质子数是3

C:中子数是1

D:电子数是2

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答案(点此获取答案解析)

B

同类题4

   Many textbooks are not written in the kind of English that we speak every day. In fact, sometimes the reading is so difficult that it almost seems like a foreign language. In a way, it is—the language of science. You should not expect to be able to read a difficult science passage the same way you read an interesting story; you should not expect to read it easily and all at once. Instead, you may have to read it several times through, catching on the meaning of difficult words, going back over difficult sentences, and finally putting the whole thing together. Do not be discourages if the whole passage don't make sense to you at first. You need to pick it apart patiently until you can understand it.
These are the steps to follow when you are reading something difficult:
   1. Start to read normally until you run into a sentence that doesn't make sense to you.
   2. When a sentence doesn't make sense, go back and read it again more slowly.
   3. Look for any word you don't know in the sentence. Try to understand their meanings using word parts and context clues(上下文线索). If necessary, look them up in the dictionary.
   4. Look at the next few sentences to see if they explain more about the sentence you are working on. Do not read very much farther ahead until you understand what is being said.
   5. Finally, read the sentence again. Try to put it into simpler words.
   6. Read through the passage once. Try to understand all the hard parts well. Then read the whole passage once more at a usual speed. This helps you to put all ides together.
   The stops sound a lot harder than they are. It is really just the normal way good readers understand anything that is difficult to read. After you have done the best you can this way, you should always feel free to ask for help from your teacher, if you have one.