A．便宜无好货，因此，好货不便宜。 B．有些动物不是哺乳类，因_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题单项选择题

A．便宜无好货，因此，好货不便宜。

B．有些动物不是哺乳类，因此，有些哺乳类不是动物。

C．所有商品都是有价值的，因此，所有有价值的都是商品。

D．有些发明家是不是科班出身，因此，有些科班出身的不是发明家。

答案

参考答案：B

解析：正确的选项须满足两个条件：第一，和题干有相同的推理形式；第二，明显前提真而结论假。只有B项同时满足这两个条件。D项满足第一个条件，但不满足第二个条件。

完形填空

Not all people like to work but everyone likes to play ．All over the world men and women，boys and girls enjoy l ．Since the days of long ago，adults(成年人)and children have called their friends together to spend 2 even days playing games．
Sports help people to live 3 ．They help to keep people healthy and feeling good．When they are playing games，people a lot 4．This is good for their health．Having 5 with their friends makes them happy．
Many people enjoy sports by watching others ．In small towns，crowds(人群)meet to watch the bicycle races or the soccer games．In big cities，thousands of people 7 to see an ice-skating show or a baseball game．
What are your favorite sports? Is the weather 8 where you live? Then swimming is probably one of your sports．Boys and girls in China love to 9 ．There are wonderful beaches and there are beautiful 70 and lakes across the country．The weather is also good for swimming．

A．buy tickets

C．read newspapers

D．hold meetings

问答题简答题

什么称为负电晕放电，什么称为正电晕放电？