If you watch the sky for about an hour after the sun goes down，you may see some "moving stars" .But they're not real stars.They're man-made satellites （人造卫星） .And the biggest of all is the International Space Station （ISS）.It is the best season to watch the ISS flying over the earth.From May to July，people can see it with their eyes.
    The ISS is the biggest satellite and scientists want to live on it.They think that the best way to learn more about space is to live there.
    When the space station is finished，it will be like a city in space.People will stay and study there with many of the things they have at home.Laboratories，living rooms and power stations are being built.The ISS is the most expensive space program.Billions of dollars are spent on it every year.
    Scientists hope that the ISS will be （B） a stepping stone for future space exploration （探测）."The ISS will help us understand the human body better，explore space and study the earth.It can help us make life on the earth better，" said Kathryn Cark，an ISS scientist.
    Sixteen countries are part of the program：the US，Russia，Canada，Japan，Brazil and 11 European countries.China isn't an ISS county，but it has helped to do some experiments.In 2003，China sent some rice up to the ISS to find out what space would do to it.

（1）任务一 列举出 ISS 所代表的两个世界之"最"。

ISS is the biggest satellite and ISS is the most expensive space program.

ISS is the biggest satellite and ISS is the most expensive space program.

（2）任务二 文中画线 they 所指代的内容是：

scientists

scientists

（3）任务三 写出划线短语"a stepping stone"的汉语意思。

一个垫脚石

一个垫脚石

（4）任务四 回答问题。
①When is the best season to watch the ISS flying over the earth？

From May to July.

From May to July.

②Why will the ISS be useful in the future？

Because the ISS will help us understand the human body better，explore space，study the earth and it can help us make life on the earth better.

Because the ISS will help us understand the human body better，explore space，study the earth and it can help us make life on the earth better.

（5）任务五 根据短文内容填空，不多于3个词。
Scientists want to live on the International Space Station because they think it is①

the best way

the best way

to learn about space.People ②

spend

spend

billions of dollars every year on it.There are ③

sixteen

sixteen

member countries in ISS，China is not one of them but China sent some rice up to the ISS to help with④

some experiments

some experiments

.