Once upon a time, people wrote letters mostly with pen and paper. But the Internet has changed all that. Among computer users today, between 50 and 90 percent of written letters take place through e-mail. That's much different from the days when everyone relied on "snail mail" . More and more new e-mail users are asking, "How can I write better e-mail message?" Here are six tips for you. (1)     Who are you writing to? Who are you writing to? A friend, a classmate, a teacher or a boss? Be sure the tone  of your e-mail message is right for the receiver. Using slang  or abbreviations  may be all right for your friends. But business letters should use full names and complete sentences. (2)     Be direct. Readers of e-mail have little patience. Say what you want to say directly. (3)     Use short sentences.  E-mail is quicker and more convenient than snail mail. It's also much easier to throw away. Don't use long sentences. Make your sentences short and clear. (4) Give enough details .  A terrible e-mail message reads like this: "Did you get my e-mail?" Someone reading this will wonder, "Which e-mail? Sent when? About what?" Today's e-mail users sometimes get many messages every day, so be sure your messages have enough details to be understood. (5) Use the subject line  well Readers see what's in the subject line of your message before anything else. Don't say "Hi, from Wang Peng"------ they can see who sent the message from the address. A short, direct explanation of the content  of your message will get you a faster answer. (6) Don't be too slow to answer. Remember that in the world of e-mail, things happen fast. If you take longer than a week to answer someone's message, it may be too late. Which of the following subject lines is the best?
Hello from Ann Hello. I sent you an e-mail About math exam You'll be pleased to get my e-mail
Question: Once upon a time, people wrote letters mostly with pen and paper. But the Internet has changed all that. Among computer users today, between 50 and 90 percent of written letters take place through e-mail. That's much different from the days when everyone relied on "snail mail" . More and more new e-mail users are asking, "How can I write better e-mail message?" Here are six tips for you. (1)     Who are you writing to? Who are you writing to? A friend, a classmate, a teacher or a boss? Be sure the tone  of your e-mail message is right for the receiver. Using slang  or abbreviations  may be all right for your friends. But business letters should use full names and complete sentences. (2)     Be direct. Readers of e-mail have little patience. Say what you want to say directly. (3)     Use short sentences.  E-mail is quicker and more convenient than snail mail. It's also much easier to throw away. Don't use long sentences. Make your sentences short and clear. (4) Give enough details .  A terrible e-mail message reads like this: "Did you get my e-mail?" Someone reading this will wonder, "Which e-mail? Sent when? About what?" Today's e-mail users sometimes get many messages every day, so be sure your messages have enough details to be understood. (5) Use the subject line  well Readers see what's in the subject line of your message before anything else. Don't say "Hi, from Wang Peng"------ they can see who sent the message from the address. A short, direct explanation of the content  of your message will get you a faster answer. (6) Don't be too slow to answer. Remember that in the world of e-mail, things happen fast. If you take longer than a week to answer someone's message, it may be too late. Which of the following subject lines is the best?
A. Hello from Ann
B. Hello. I sent you an e-mail
C. About math exam
D. You'll be pleased to get my e-mail
Answer: