The moon is about 384 000 kilometres away from the earth.A plane cannot fly to the moon because the air 42 only 240 kilometres away from the earth.But something can fly even when there is no 43 .That is a rocket(火箭).

　　44 does a rocket fly?There is gas(气体)in it.When the gas is made very 45 inside the rocket,it will rush out of the end of rocket,so it can make the rocket 46 the sky.

　　Rockets can fly far out into space.Rockets with people in them 47 the moon.Several rockets without people in them have 48 to another planet(行星)much farther away than the moon.One day rockets 49 be able to go to 50 place in space.

　　36.A.know B.mean

　　C.say D.point

　　37.A.without B.behind

　　C.between D.over

　　38.A.before B.after

　　C.later D.ago

　　39.A.how long B.how heavy

　　C.how wide D.how big

　　40.A.So B.Because

　　C.After D.But

　　41.A.men B.satellites

　　C.spaceships D.news

　　42.A.gets B.reaches

　　C.arrives D.stays

　　43.A.air B.space

　　C.cloud D.smoke

　　44.A.Where B.When

　　C.How D.What

　　45.A.cook B.cold

　　C.hot D.warm

　　46.A.to run out of B.run out of

　　C.to fly up into D.fly up into

　　47.A.have been to B.have gone to

　　C.have been in D.have gone in

　　48.A.visited B.flown

　　C.risen D.fallen

　　49.A.can B.may