题目

 E-mail: Party From: 11350@csu.edu (Lisa Raster) To: Jenny Smith@ yahoo.com (Jenny Smith) Subject: Party!!! __________________________________________________. Hi Jenny. Listen, I'm having a party this Friday at my house. Just a few friends will be there. Mostly they 're from the office. My boyfriend Tom will also come. He's a nice guy. I want you to meet him. Do you want to come? We'll play games and talk. Then we'll eat dinner. Everybody will bring food or drinks. The party is this Friday. It starts at 4:00 PM. It will end at 8 or 9 PM. We'l1 have a great time! Can you come? I hope s给出下列四种从集合A到集合B的对对应：其中是从A到B的映射的是A.（1）（2）B.（1）（2）（3）C.（1）（2）（4）D.（1）（2）（3）（4）