On the Earth, everyone has a home. While in space, there is also a home. It is nearly as big as a soccer field and larger than a six-bedroom house. It is the International Space Station(ISS).
The ISS is home to astronauts. Usually, there are three to six astronauts on board. Astronauts in the space station are very busy. They do many science experiments in biology and physics, and study the effects on the human body after long exposure(暴露) to microgravity(微重力). Sometimes they go on spacewalks to work outside the station.
As a groundbreaking scientific research facility, the ISS benefits(使受益) people on the Earth. Robots on the ISS have inspired medical technology. Now it is possible for patients to receive certain surgery(外科手术) by a robotic arm, which performs better than humans. The ISS also helps to watch the Earth’s ecosystems(生态系统) and warns us of volcano eruptions(火山爆发) and earthquakes.
For children, the ISS plays an important part in education. Children can ask astronauts in the ISS any question with the help of satellites. For example, what do you eat? How do you sleep? This is a good way to improve children’s interest in science and technology.
The ISS is expected to remain in operation until at least 2020, China Daily reported. Russia may build a new space station to replace it at that time.
In the future, space will be home to more stations like the ISS. China is also planning to build its own space station, and the launch of Tiangong-1 in 2011 was the first step. It is expected that China will complete the space station by 2023.

The International Space Station(ISS)
Home to astronauts (5-6 astronauts ____ )	1.They do many experiments in different scientific fields. 2.They study___ on human body with nearly zero gravity. 3.They go on spacewalks.
Benefit people on the Earth	1. Robots on the ISS have inspired _____. 2. Help to watch the earth’s ecosystems. 3. Warns us of volcano eruptions and earthquake.
Help children in education	A good way to children’s interest in science and technology.
______________ marks the first step of China to build its own space station.