一，故事原文：
142 现在完成时的基本概念及其“已完成”与“未完成”含义
“Forward, forward … good! Forty feet. Drift to the right a little. Okay, Engines stop. The Eagle has landed!”
A visit to the moon has been a dream of human beings for thousands of years.
The world has listened to the news reports about Apollo 11 for several months. For Americans, they have waited for the great day since 1961.
143 一般现在时替代现在完成时的情形
It was in that year that President Kennedy announced a national goal in his speech to the American people: “By the end of 1960s, the United States of American is to land a man on the moon and return him safely to the earth.”
It is eight yeas since President Kennedy was killed.
144 从现在向过去追溯的时间段与现在完成时（本节无相应故事句，纯讲解）
145 瞬间动词、持续性动词与现在完成时
In the past eight years, people haven’t got any satisfactory explanation about his death, thought they have asked form time to time.
146 现在完成时与时间状语连用与否时表达的不同含义
They have been keen for the explanation but in vain.
147 序数词、最高级和现在完成时的连用
However, they never forget the youngest president in American history. Today, a million people have made their camps around the launching site called Cape Kennedy.
It is the first time that a human being has ever set foot on another object in space. It is also the most exciting TV program people have ever watched.
148 说话时仍处于“现在”时间段中的现在完成时
Americans have sent three Apollo spaceships to explore the moon this year.
149 have been to与have gone to的区别
Apollo 9 and Apollo 10 have been to the moon orbit to get the necessary data. Now Apollo 11 has gone to the moon.
150 现在完成时与一般过去时的区别
The astronauts have prepared for the journey for seven years. During the past few months, they have also practised landing on the moon.
Following the voyage of Apollo 9, engineers decided that one more test flight was needed. They wanted to test the landing module near the moon. Three astronauts did so during the flight of Apollo 10.
151 现在完成时可以表示将来完成时的意思
It is certain that people will visit other planets when they have mastered more advanced technologies.
二 详细讲解：
现在完成时
为了讲解方便，我们把第一个人踏上月球的那一时刻作为“现在”时刻。
142 现在完成时的基本概念及其“已完成”与“未完成”含义
[故事联结句： “Forward, forward … good! Forty feet. Drift to the right a little. Okay, Engines stop.”
“向前，向前……好！40英尺、向右偏一点儿。OK。关闭引擎。”]
“The Eagle has landed!”
鹰已着陆。
这个句子包括了两个含义。
第一，在说这句话之前的过去时间里，发生了一个动作——“着陆”。
第二，这个发生在过去的动作对“现在”产生了影响——人类现在在月球上了。
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