问题 选择题

以NA表示阿伏加德罗常数,下列说法中正确的是[ ]

A.53g碳酸钠中含NA个CO32-

B.0.1molOH-含NA个电子

C.1.8g重水(D2O)中含NA个中子

D.标准状况下11.2L臭氧中含NA个氧原子

答案

答案:B

单项选择题
改错题

对标有题号的每一行做出判断:每行只有一处错,按下列情况改正:该行多一个词:把多余的词用斜线(\)划掉,在该行右边横线上写出该词,也用斜线划掉。该行缺一个词:在缺词处加一个漏字符号(),在该行右边横线上写出该加的词。该行错一个词:在错的词下划一横线,在该行右边横线上写出改正后的词。

Dear Casey,

You asked in your last letter about my spare                               

time activities. Well, I like much more than one,                                 76._____________

such as painting and model making, so my favourite                           77._____________

is dancing. I started when I was eight year old,                                78._____________

and it is a great fun! Dancing is not difficult. If                                79._____________

you want to do it good, you need to find a good                              80._____________

dancing teacher and taking lessons regularly.                                      81._____________

That’s I did and I also had to take exams every                                    82.______________

six months. Now, I had stopped going to lessons.                                83.______________

But I sometimes take part performances at the                                    84.______________

school, that I really enjoy very much.                                                85.______________