听力原文：W: Well, it seems to me that everybody's talking about E-mail nowadays. When you exchange cards with others, you'll feel out of time and start at a disadvantage if your card hasn't an E-mail address on it. M: I wouldn't be surprised, because, you know, it's the easiest way to communicate with other users over a network. W: Is it? But I was told that we must set up an E-mail system on the network before we can communicate with other users. Is that true? M: Yes, it's not tough to create such a system. However, you need some hardware and software to support it. W: Let me know the hardware needed first. M: A computer and a line that connects your computer with the Internet. W: All right. I was told that I need an account for my E-mail. Where can I get it? M: You can contact an ISP, I mean an Internet Service Provider, to get an account. W: How much do I have to pay for it? M: It varies. You can also get a free E-mail account if you don't have to consider too much for the security of your mails. I know many people prefer free E-mails and they say their correspondence through that kind of account doesn't involve commercial information needed to be strictly kept secret. You can get such a free account simply at home if you have got access to a website with such a service. W: It's so convenient. I may prefer the free E-mail. What about the software? M: You don't need any additional software. Just the IE, the Internet Explorer, bound with Windows, the operating system. W: Thank you so much for your help. Questions 19 to 22 are based on the conversation you have just heard. 19. According to the man, why is E-mail so popular? 20. Which is the disadvantage of a free E-mail account? 21. What is the necessary software to support the E-mail system? 22. What will the woman probably do after the conversation? (23)