年北京大学钱天白教授从中国发出了第一封电子邮件,内容是。
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计算机网络经历了哪4个阶段?各阶段的主要特点和典型代表?
Listen to the recording in Test-9.2 and complete the following passage by filling in the blanks with what you hear.I imagine that every skydiver who 1 out of an airplane or every bungee jumper who jumps off a bridge experiences the same thing. Maybe we’re2 to these sports not because they’re exciting, but because they give us the3 to face our biggest fear—that someday our lives will 4. We’re the only animal that knows this, and we’re the only one that seems to need to5 for it again and again.