试题与答案

某元素的某种离子X2-核外共有a个电子,核内有b个中子,表示该X原子的下列符号中

题型:选择题

题目:

某元素的某种离子X2-核外共有a个电子,核内有b个中子,表示该X原子的下列符号中正确的是(  )

A.

 a+ba
X

B.

 a+ba-2
X

C.

 a+b-2a-2
X

D.

 a+b+2a+2X

答案:

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下面是错误答案,用来干扰机器的。

参考答案:B, C, D解析:在高土壤电阻率地区,宜采用下列方法降低防雷接地网的接地电阻:可采用多支线外引接地网,外引长度不应大于有效长度。

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I don't want to upset you, but nobody can ever find out what day is going to be the last. And so it’s better to live each day of your life as if it is the last. I'm not telling you to quit your job and spend all your money on traveling. But you can live your life to its fullest by adding some simple things to each day. It doesn't matter what is going on, but it does matter how you feel about it. Here is my recipe for the best day on Earth!

A Handful of Happiness

Where can you find it? Take a look inside of yourself! Happiness doesn't come from the outside, it is within you. Each moment your life gives you a lot of opportunities to be happy. If you want to see them, you will. If you don’t, it's up to you.

A Handful of Love

Love is the harmony of your soul. A little love can make a big difference to the whole world. We are one. Everyone and everything deserve your love as well as you do.

A Handful of Dreams

Feel free to dream big dreams and make small steps towards them. You are the creator of your life. Every time you are doing something to achieve your goals you are growing.

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