题目内容：
根据下列题干，回答题In the following essay, each blank has four choices.Choose the best answer and write down on the answer sheet.
Communicating via Email is by far the most common Internet activity.You can (1) with anyone in the world who has an Internet address or Email (2) with a system connection to the Internet.All you need is (3) the Internet and an Email program.Two of the most widely used Email programs are Microsoft's (4) and Netscape's Navigator.A typical Email message has three basic (5) : header, message, and signature.
请选择（1）处最佳答案
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