英语阅读理解,快,we all live on the earth．The earth turns round once

英语阅读理解,快,
we all live on the earth．The earth turns round once a day．As it turns,some people see sunset and night comes to their houses．
The earth moves in another way,too．If it travels round the sun in an orbit(轨道)towards (向着)the sun,it is summer on that part of the earth．Half a year later,the earth goes round to the other side of its orbit．That part of the earth is now farther away from the sun,and has its winter,and the other part has its summer．Between summer and winter,both halves of the earth are the same distance(距离)from the sun．Then they have spring and autumn．As the earth goes round in its orbit,we have our four seasons go on and on．
( )46．We can see sunrise and sunset because ．
A．the sun is near to us
B．the earth turns round every day
C．the sun goes out of the clouds in the daytime and into them at night
D．the earth moves round the sun
( )47．There are four seasons in a year because
A．the earth moves round the sun
B．the sun turns round the earth
C．the sun moves from one place to another
D．the earth travels nearer and nearer to the sun
( )48．When the earth goes round the sun,we have on the part that is towards the sun．
A．spring B．summer C．autumn D．winter
　( )49．When we have winter,the part of the earth that we stand on is ．
A．near the sun
B．nearer to the sun
C．farther away from the sun
D．the some distance as the other part from it
( )50．When both halves of the earth are the same distance from the sun,we have ．
A．spring and autumn B．spring and winter
C．summer and winter D．summer and antumn