Cell phones are very useful and they are great fun．But cell phones do have risks．If you have one，it's
（66） （必须的） to understand these risks，and learn how to enjoy your phone safely．Sending messages can be one of the most wonderful（67）w to keep in touch with your friends．But some people can also send rude messages．Do not（68） if you receive them．I （69） ，save the messages and show them to your teachers or parents．If you receive a message saying that you （70）w in a big prize，don't believe it．
Sending pictures from a cell phone is（71） （免费的），fast and fun．But make sure you send only pictures that you wouldn't mind other people（72） （看见）．And you may have an accident if you try to use your cell phone while crossing the（73） ．It's dangerous because there are many cars and buses．
With your parents'help，you can keep your cell phone's（74） ．You won't have to worry about receiving rubbish calls or messages!Remember not to talk on the cell phone too often or too long．Turn （75） your cell phone when you sleep．The sounds of rubbish messages may wake you up．