It was in 1969 ______ two Americans went to the moon by spaceship.

A．when            B．that              C．at that time        D．just then

It was in 1969           two Americans went to the moon by spaceship.

A．when        B．that        C．at that time        D．just then

It was in 1969 ________ two Americans went to the moon by spaceship.

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It was in 1969 ________ two Americans went to the moon by spaceship.

[　　]

For  centuries  people dreamed  of going  into  space.This dream began to seem possible when high­flying rockets were built in the early 1900s.

In 1903 a Russian teacher named Konstantin Tsiolkovsky figured out how to use rockets for space travel.His plan was the first one in rocket science to use correct scientific calculation.About 30  years  later，a U．S.scientist  named  Robert  Goddard built the first rockets that could reach high altitudes.During World War Ⅱ，German scientists built large rockets that could travel very far and carry dangerous explosives.After the war，scientists from Germany went to the United States and the Soviet Union to help those countries build space rockets.

These two countries were soon racing to get to space first.Each of these countries wanted to prove that it was stronger and more advanced than the other one.Both countries also had powerful bombs.People in the United States were worried when the Soviets were first to launch a space satellite，which was called Sputnik.The Soviets were also first to send a person into space.Yury Gagarin orbited the earth in the Vostok I spaceship in 1961.

The US government set a goal for its space program to be the first country to put a person on the Moon.The U．S.space program built a series of Apollo spaceship.These vehicles were powered by huge Saturn 5 rockets.In 1969 Apollo Ⅱtook three men to the moon successfully.Nell Armstrong became the first person to walk on the Moon.

The Soviets  may have lost the race to fly people to the Moon，but they built the first space station in 1971.The United States also built a space station.The space stations allowed people to live and work in space.Then the Soviet Union and the United States cooperated to hook two spaceships together in space.This action ended the “space race”．Today a much larger space station，built by several countries together，orbits Earth.

Another new way to go to space is  by space shuttle.A space shuttle，first made in the United States in 1981，looks like an alrplane.Astronauts who fly spaceships have used shuttles to help put satellites into space.