READING PRACTICE 1

1
Sound travels in waves through the air like waves through the water ; the higher the wave , the greater its power . The waves are alternate rings of compressed and rarefied air moving away from a central source at a constant speed . As each wave of first compression and then rarefaction encounters an object , it exerts a force – a push and then a pull- on the object . That is why sound can break a glass or cause a screen to vibrate.
The greater the number of waves a sound has , the greater its frequency is . The strength or intensity of sound , sound level , is measured in decibels (dB) . The decibel unit is named after Alexander Graham Bell , the inventor of the telephone and an important researcher into the nature of sound . Because hearing varies widely , what may seem loud to one person may not to another . Although loudness is a personal judgment , precise measurement of sound is made possible by use of the decibel scale . This scale of Sound Levels and Human Response measures sound pressure or energy according to international standards .
It can be inferred from the passage that a sound measured at 100 decibels is louder than
any other sound ever measured
a sound measured at 110 decibels
a sound measured at 80 decibels
the machine measuring it
It can be concluded from the passage that
sound waves can be measured scientifically
sound has no physical effect on any object
everyone judges loudness the same way
the decibel scale is a purely subjective device
Sound waves move outward from a central point at
varying speeds
a speed of 1,181 kilometers per hour
greater and greater speeds
a steady, continuous speed
During a loud thunderstorm, a window may rattle because
lightening strikes the glass with force
the sound of the rain is heard through the glass
the air is colder on one side of the glass than on the other
the claps of thunder create powerful sound waves that exert pressure on the glass
The term decibel comes from
the intensity of twelve bells
the inventor of the telephone
the inventor of the hearing aid
a term for rarefied air
2
HOW TO TRANSPLANT A TREE
In most cases, you can transplant a tree successfully, at any time, if you follow the instructions for planting a tree. The most important thing is to dig out enough roots, but this process is difficult with a large tree.
When you dig out the tree, leave a ball of earth around its roots. This ball of earth should measure about a foot wide for every inch of the tree trunk’s diameter. Dig deep enough to avoid cutting off too many taproots.
It is wise to call in a professional tree expert to transplant a tree more than a few inches in trunk diameter.
Transplanting a tree is
very different from planting a tree
so difficult that an expert should always be called in
much like planting a tree
done successfully in the right seasons
The larger the trunk of the tree you are transplanting
the less it matters whether you call in a tree expert.
The more you should avoid cutting off the taproots
The larger the ball of earth you must leave around the roots
The easier it is to dig out sufficient roots
The taproots are
the heaviest roots
the principal, deepest roots
the ball of earth
the same width as the trunk’s diameter
The best time for transplanting a tree is
A. spring C. winter
B. fall D. any season
5. To decide whether you can successfully transplant a tree yourself, you should
A. select your location carefully
B. measure the ball of earth around the tree roots
C. measure the diameter of the tree trunk
D. cut off many taproots as you can reach
3
The influenza virus is a single molecule composed of millions of individual atoms. While bacteria can be considered as a type pf plant, secreting poisonous substances into the body of the organism they attack, viruses, like the influenza virus, are living organism themselves. We may consider them as regular chemical molecules since they have strictly defined atomic structure; but on the other hand, we must also consider them as being alive since they are able to multiply in unlimited quantities.
According to this passage, bacteria are
A. poisons C. larger than virus
B. very small D. plants
2. The writer says that viruses are alive because they
A. have a complex atomic structure
B. move
C. multiply
D. need warmth and light
3. The atomic structure of viruses
A. is variable
B. is strictly defined
C. cannot be analyzed chemically
D. is more complex than that of bacteria





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There are more than 3000 languages in the world today , but only