Do you want to be an astronaut？Let's know more about astronaut's life.First of all，most of the astronauts are pilots.Also，astronauts need a healthy body and mind to get on with others ①_____they need spend much time in a small space with others.
    Life on a spaceship is hard.The food is dry.There is no running water.And to sleep，you must cover your eyes because the sun rises every 90 minutes on the Space station.You also have to tie yourself to something，so you don't fly away.
    Astronauts will have to solve different kinds of problems in space，so they must learn many subjects，including math，physics and many more.In this way，they will know what to do when there is a problem in ②_____.
    To practice space walking and living in a space，astronauts always wear a 200-kilogram suit and stay underwater for six or seven hours without eating or going to the toilet.This is like working during a spacewalk.Their training usually lasts for a year.
    In space，human's bones and muscles（肌肉） become thin and weak.The heart gets smaller and changes shape.Astronauts often get back pain because they could grow taller in space. Astronauts must do a lot of exercise in space to stay away from health problems.All of them are heroes（英雄）.

（1）Why must astronauts learn many subjects？（no more than 15 words）

Because astronauts will have to solve different kinds of problems in space.

Because astronauts will have to solve different kinds of problems in space.

（2）How long does a astronaut's training usually last？ （no more than 10 words）

For a year.

For a year.

（3）Fill in each blank in the passage with one proper word.
①

because

because

②

space

space

（4）Translate the underlined sentence in Paragraph 5 into Chinese.

宇航員在太空中必須進(jìn)行大量的鍛煉以避免健康問(wèn)題。

宇航員在太空中必須進(jìn)行大量的鍛煉以避免健康問(wèn)題。

（5）After reading the passage，what do you think of our Chinese astronauts？

They are great.

They are great.