Science has told us so much about the moon that it is quite easy to form an idea of what it would be like to go there. It is certainly not a friendly place. As there is no air or water, there can be no life of any kind. Mile after mile there are only plains(平原) of dust with mountains around them. Above, the sun and stars shine in the black sky. If you step out of the mountains shadows, it will mean moving from terrible cold into great heat. The moon is also a very silent(安静的) world, for sound waves (声波)can only travel through air. But from the moon, you can see a friendly sight(景色). Our earth is shining more brightly than the stars. It looks like a large ball, coloured blue and green and brown.
(   ) 16.What kind of place is the moon?
A. It is a friendly place.             B. It is a lively place.
C. It is a nice place for man to live.    D. It is a lifeless place.
(    ) 17.Temperatures on the moon____.
A. are usually the same everywhere   B. Are always very low
C. can be very different              D. are usually very high
(    ) 18.The moon is a silent world because____.
A. there is no life there              B. there is no air there
C. there is no water there             D. there is not a green tree there
(   ) 19. When we look from the moon, the sky is ____.
A.          blue          B. black         C. green           D. brown
(  ) 20. Mile after mile there are only plains of dust with mountains around them. The word “dust” means “___”.
A. dump (垃圾堆)    B. dry earth (泥土)    C. land       D. field

In old times，man considered lightning to be one of the great mysteries（神秘事物）of nature．In fact a single flash of lightning 1.6 kilometers long has enough electricity to light one million lamps．
The American scientist，Benjamin Franklin，was the first to suggest that lightning is in fact electricity formed between the earth and clouds high above．It happened in 1752．In the same year，he also built the first lightning rod（避雷针）to protect buildings from being struck by lightnings．
Modern science has discovered that lightning is very strong and powerful．A lightning between a cloud and the earth may be as long as 13 kilometers，and travels at a speed of 30 million meters per second．Scientists have the opinion that there are about 2000 million flashes of lightning per year．In the United States alone，it kills almost one person per day．
The safest place to be in during an electrical（电的）storm is a closed car．Outside，one should go close to low ground for cover and not stop under a tree．Also one should stay out of water and away from metal fences．Inside a house people should keep away from open doorways and windows and not touch wires or metal things．
【小题1】From this passage we know lightning is____．

A．one of the great mysteries of nature．

B．electricity high above the earth．

C．a kind of light．

D．the sound from the clouds．

【小题2】In the U．S____．

A．every person can see lightning every day．

B．at least one person is killed by lightning every day．

C．there are about 6 million flashes of lightning per year．

D．about one person per day dies from lightning．

【小题3】During a lightning storm，it would be best if you____．

A．stand under a tree．

B．go outside．

C．stay in a closed car．

D．stop near windows．

【小题4】A lightning rod can______．

A．prevent accidents caused by lightning

B．stop lightning

C．protect buildings from being washed away．

D．delay the coming of lightning

【小题5】A lightning between a cloud and the earth may be 13 kilometers long，and travels at
a speed of ______．

A．30 kilometres per second．

B．3000 kilometres per second

C．3 kilometres per second

D．30，000 kilometres per second

In old times，man considered lightning to be one of the great mysteries（神秘事物）of nature．In fact a single flash of lightning 1.6 kilometers long has enough electricity to light one million lamps．
The American scientist，Benjamin Franklin，was the first to suggest that lightning is in fact electricity formed between the earth and clouds high above．It happened in 1752．In the same year，he also built the first lightning rod（避雷针）to protect buildings from being struck by lightnings．
Modern science has discovered that lightning is very strong and powerful．A lightning between a cloud and the earth may be as long as 13 kilometers，and travels at a speed of 30 million meters per second．Scientists have the opinion that there are about 2000 million flashes of lightning per year．In the United States alone，it kills almost one person per day．
The safest place to be in during an electrical（电的）storm is a closed car．Outside，one should go close to low ground for cover and not stop under a tree．Also one should stay out of water and away from metal fences．Inside a house people should keep away from open doorways and windows and not touch wires or metal things．
【小题1】From this passage we know lightning is____．

A．one of the great mysteries of nature．

B．electricity high above the earth．

C．a kind of light．

D．the sound from the clouds．

【小题2】In the U．S____．

A．every person can see lightning every day．

B．at least one person is killed by lightning every day．

C．there are about 6 million flashes of lightning per year．

D．about one person per day dies from lightning．

【小题3】During a lightning storm，it would be best if you____．

A．stand under a tree．

B．go outside．

C．stay in a closed car．

D．stop near windows．

【小题4】A lightning rod can______．

A．prevent accidents caused by lightning

B．stop lightning

C．protect buildings from being washed away．

D．delay the coming of lightning

【小题5】A lightning between a cloud and the earth may be 13 kilometers long，and travels at
a speed of ______．

A．30 kilometres per second．

B．3000 kilometres per second

C．3 kilometres per second

D．30，000 kilometres per second