网络是由节点和连线构成，表示诸多对象及其相互联系。在数学上，网络是一种图，一般认为专指加权图。
A: hi, dave! What’s up?
B: oh, not much. What have you been doing recently, cathy?
A: I’ve been chatting online a lot with friends.
B; where do you go to chat?
A; I usually use yahoo messager. What about you?
B; I’ve never chatted online before.
A: what?? How is that possible? Why not?
B: well, my computer is really old, so most software isn’t compatible with my computer.
A; do you want to come over to mine? I can show you how to use it.
B: how long does it take to download mp3 files?
A: not very long at all. I usually download at least 30 a day.
B; do you ever download any tv progmp3s or movies?
A; sure, I’d say that I download at least on progmp3 a day.
B: do you think you could download some for me?
A: sure, just let me know what you want and I can burn it onto a cd for you.
B; let me see… I’ve heard a lot about a show called friends.
A; no problem. Did you know that there are many friends forums online?
B: what’s a forum?
A: it’s a place you can go to online where you can chat to other people who have similar interests as you.
B; do the friends’ stars ever show up there?
A; sometimes, people say they are the friends stars, but you never know who you’re talking to. For all I know, Jennifer aniston is really an old fat man.
A: ha ha ha…
A：Have you ever tried shopping online?
你在网上买过东西吗？
W：No, never. I perfer to actually see and touch what I'm buying before I pay for it, especially for clothes and shoes.
没买过，我还是喜欢买之前亲自感受一下，特别是衣服和鞋。
A：That's right. Seeing is believing.
没错，眼见为实。
W：I've heard some friends say when they get the article, it's quite different from what they see on the website advertisement.
我听朋友说过，他们在网上买到的东西和网站广告上看到的很不一样。
A：That happens. Without close quality examination, we may encounter fraud, and the e-shop may suddenly disappear.
确实有这种事，不好好检查质量，可能会买到假货；网站也没准会突然消失。
W：What's more, it's not always so safe for us to pay online as hackers might steal the user name and password.
而且网上付费有时也不安全，黑客可能会偷走用户名和密码。
A：It's said that some measures have been taken to deal with this problem. Paying online is much safer than before, but I still have the feeling that it's not safe enough.
听说已经出台措施解决这个问题了。现在网上付费比以前安全多了，但是我还是觉得不够安全。
W：I can't agree more. that's why I only do street shopping.
你说的太对了，所以我只在实体店买东西。
A：Me too. Sometimes I surf online shops to check some related information, and then go to a physical store to do the actual shopping.
我也是，有时候我会逛一下网店，查一下产品信息，然后到实体店里去买。
W：That's a good idea.
这法子不错。
A: what’s up?
B: not much. Its frezzing in Beijing.
A: u should come to Bangkok. We’ve got lovely weather here.
B: great! R y inviting me?
A: laughing out loud.
B: be right back.
A: where r u going?
B; bathroom.
A; ok. I’m going to go to bathroom too. Talk to you later.
Note: when people chat online, they often shorten words. Use abbreviations, use lower case letters, and rarely use punctuation marks, especially apostrophe marks.