题干

已知集合A=z|z=
1
-
i
1
+
i
n
,nN
,则集合A的元素个数为 (  )      

A:2

B:3

C:4

D:无数个

上一题 下一题 0.0难度 选择题 更新时间:2017-06-08 12:15:43

答案(点此获取答案解析)

C

同类题5



    I really only meant it as a joke. I wasn't trying to steal anything honestly.
   My friend Matthew started bringing his new cell phone to class last week. He was walking around bragging (吹嘘) about it to everyone. He was saying, "My cell phone can download the newest 1 off the Internet."Then he 2everyone by downloading a game and starting to play it. The pictures and sound were really 3.4 class, he would use his cell phone to watch TV. The rest of us didn't have a phone like  5, so we had to crowd(拥挤) around him. I was just trying to see the screen, 6 there were so many other kids that I could not see it clearly. I was getting really jealous.
   But then yesterday, he forgot his cell phone at the end of class. He left it right on his desk. 7 noticed it was there except me. I decided to teach him a lesson. I took his phone quietly off the desk, and put it in my own bag. My 8 was to give it back to him the next day. I 9  wanted to see his reaction (反应). Maybe he would stop being such a show-off.
   But this morning he rushed into class, screaming and yelling (吼叫). He was very 10  and almost mad. He started accusing (指责) different people of  11 his phone, but I had it in my  12  the whole time. He even started fighting with another classmate 13  Matthew was sure that person had taken it. The teacher sent them to the headmaster's office. They  14   got in a lot of trouble. Now I don't know what to 15 ! If I tell him that I took the cell phone, he'll think I stole it. If I don't tell him, then I really did steal it. How did I get into such a trouble?