45. It can be concluded from the passage
that ________.
A. safety screens are of poor quality
B. working at a VDU for a long time is
good for one’s health
C. more and more British offices will use word processors
D. British companies will need fewer and fewer managers
B
Although April did not bring us the rains we
all hoped for, and although the Central Valley
doesn’t generally experience the sound and lightning that can go with those
rains, it’s still important for parents to be able to answer the youthful
questions about thunder and lightning.
The reason these two wonders of nature are
so difficult for many adults to explain to children is that they are not very
well understood by adults themselves. For example, did you know that the
lightning we see flashing down to the earth from a cloud is actually flashing
up to a cloud from the earth? Our eyes trick us into thinking we see a downward
motion when it’s actually the other way around. But then, if we believed only
what we think and we see, we’d still insist that the sun rises in the monring
and sets at night.
Most lightning flashes take place inside a
cloud, and only a relative few can be seen jumping between two clouds or
between earth and a cloud. But, with about 2,000 thunderstorms taking place
above the earth every minute of the day and night, there’s enough activity to produce about 100
lightning strikes on earth every second.
Parents can use thunder and lightning to
help their children learn more about the world around them. When children
understand that the light of the lightning flashing reaches their eyes almost
at the same moment, but the sound of the thunder takes about 5 seconds to
travel just one mile, they can begin to time the interval(间隔) between the flash and the crash to learn how close they were to
the actual spark(闪光).
