在因特网电子邮件系统中，电子邮件应用程序( )。
A．发送邮件和接收邮件通常都使用SMTP协议
B．发送邮件通常使用SMTP协议，而接收邮件通常使用POP3协议
C．发送邮件通常使用POP3协议，而接收邮件通常使用SMTP协议
D．发送邮件和接收邮件通常都使用POP3协议
参考答案：B
解析： 电子邮件应用程序在向邮件服务器传送邮件时，使用简单邮件传输协议(Simple Mail Transfer Protocol SMTP)。而从邮件服务器的邮箱中读取时可以使用(Post Office Protocol, POP3)协议或(Interactive Mail Access Protocol, IMAP)，至于电子邮件应用程序使用何种协议读取邮件则决定于所使用的邮件服务器支持哪一种协议。我们通常称支持POP3协议的邮件服务器为POP3服务器，而称支持IMAP的服务器为IMAP服务器。
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| There was a woman in Detroit, who had two sons. She was worried about them, especially the younger one, Ben, because he was not doing well in school. Boys in his class played jokes on him because he seemed so 1 . The mother 2 that she would help her sons to do 3 in school by herself. She told them to go to the Detroit Public Library to 4 a book a week and do a book report for her. One day, in Ben's class, the teacher held up a rock and asked 5 anyone knew it. Ben put up his hand and the teacher let him 6 ."Why did Ben raise his hand?" all of his 7 whispered (耳语) and wondered. "He 8 said anything. What could he possibly want to say?" To their surprise, Ben not only 9 the rock, but also said a lot about it. He 10 other rocks in its group and even knew 11 the teacher had found it. The teacher and the other students were 12 . Ben had learned this from doing one of his book 13 . Later Ben became the 14 student of his class. When he finished high school, he went to Yale University and 15 became one of the best doctors in the United States. | ||||
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