某校九年级学生毕业时，每个同学都将自己的相片向全班其他同学各送一张留作纪念，全班共送了1640张相片．如果全班有x名学生，根据题意，列出方程为____ ．

“有事情，发微信”“找好友 ，摇一摇”“有趣事，朋友圈里晒一晒”“微信摇一摇，朋友自然来”。眼下，使用微信交友已经成了很多年青人热衷的交友方式。然而，“摇一摇”除了摇来了朋友，也摇来了凶险和危机。近来，由于微信交友引发的抢劫、诈骗、勒索的犯罪数量增多。

C

    Some children wish to be writers some day. They want to write stories or books for people to read. That's good! It's good to write something for people to read! But they should know that they need to be good readers first before they are really good writers. They should read a lot of books, instead(代替) of watching TV and spending a lot of time playing games when they are free.

    There is more fun in reading, and you want to look for more books to read.

    Before you decide(决定) to be a good writer, you'd better say to yourself, "I must read more and more!"