如果正整数n，使得n+17n-7也是正整数，那么这样的正整数n有______个．

阅读理解。

     In Japan many old people don't live with their children. They have no one to talk to. Their life is very

boring. Now a new robot (机器人) comes. It has two big eyes and ears. It looks like a white teddy bear.

There are four cameras and a sensor (传感器) in the robot. It can draw planes. It can also use the

Internet (网络) to find some pictures and draw them down. It is a good friend for the old. It will help them a lot and it can chat (聊天) with them. It can answer some questions,too. Sometimes it also helps them to

find glasses. It doesn't mind listening to the same stories again and again. Lots of children also like it. They can play with it when their parents go to work.

1. In Japan many old people _____ talk with others.

A. usually  

B. often    

C. seldom  

D. always

2. What do many old people think of their lives in Japan?

A. Busy.  

B. Boring.  

C. Interesting.  

D. Colorful.

3. What color is this new robot?

A. White.  

B. Green.  

C. Black.  

D. Brown.

4. How many cameras does the robot have?    

A. 2.  

B. 3.  

C. 4.  

D. 5.   

5. What things can't the robot do?    

A. Chat with others.   

B. Draw pictures.     

C. Use the Internet.     

D. Do housework.    

“宾夕法尼亚州的乡下人吃野草根、蒲公英；肯塔基州的人吃紫罗兰叶、野葱、勿忘我草、野莴苣以及一向转给牲口吃的野草。城里的孩子母亲在码头上徘徊，一有腐烂的水果蔬菜扔出来，就上去同野狗争夺。……人们还看到，有人全家走进垃圾堆捡骨头和西瓜皮来啃。……”出现上述现象的原因是： [ ]

A、第一次世界大战对美国的打击

B、1929——1933年经济危机对美国的打击

C、第二次世界大战对美国的打击

D、冷战对美国的打击

BOCNET企业服务涉及的汇划类交易全部为系统联机自动处理，不提供交易落地人工干预机制。（）

零序电压的特点是（）。

黑格尔说：“中国人除了皇帝外都不知道自己是自由的，古希腊人有一部分知道自己是自由的。”在古希腊，知道自己是自由的这一部分人是指（）

A.妇女

B.外邦人

C.成年男性公民

D.奴隶