（初めに右欄で英語を１つ選び、続いて選択肢から１つを選んでください。やり直すときは、英語を選び直すことから始めてください。右の［単語帳］を参考にすることもできます。）For the next few years, both the United States and Soviet Union continued their exploration of the moon. Yet the question remained: which one would be the first to put a man there. In December, nineteen sixty-eight, the United States launched Apollo eight with three astronauts. The flight proved that a spacecraft could orbit the moon and return to Earth safely.
The Apollo nine spacecraft had two vehicles. One was the command module. It could orbit the moon, but could not land on it. The other was the lunar module. On a flight to the moon, it would separate from the command module and land on the moon's surface. Apollo ten astronauts unlinked the lunar module and flew it close to the moon's surface.
After those flights, everything was ready. On July sixteenth, nineteen sixty-nine, three American astronauts lifted off in Apollo eleven. On the twentieth, Neil Armstrong and Edwin Aldrin entered the lunar module, called the Eagle. Michael Collins remained in the command module, the Columbia.
The two vehicles separated. It was a dangerous time. The Eagle could crash. Or it could fall over after it landed. That meant the astronauts would die on the moon.
Millions of people watched on television or listened on the radio. They waited for Armstrong's message: "The Eagle has landed." Then they waited again. It took the astronauts more than three hours to complete the preparations needed to leave the lunar module.
Finally, the door opened. Neil Armstrong climbed down first. He put one foot on the moon. Then, the other foot. And then came his words, from so far away:
NEIL ARMSTRONG: "That's one small step for (a) man; one giant leap for mankind."
Armstrong walked around. Soon, Aldrin joined him. The two men placed an American flag on the surface of the moon. They also collected moon rocks and soil.
When it was time to leave, they returned to the Eagle and guided it safely away. They reunited with the Columbia and headed for home. The United States had won the race to the moon.