A pilot cannot fly a plane by sight alone. In many
conditions, such as flying at night and leading in dense fog, a pilot must use
radar, an alternative way of navigating. Since human eyes are not very good at
determining speeds of approaching objects, radar can show a pilot how fast
nearby planers are moving. The basic principle of radar is exemplified by what
happens when one shouts in a cave. The echoes of the sounds against the walls
help a person determine the size of the cave. The echoes of the sounds against
the walls help a person determine the size of the cave. With radar, however,
the waves are radio waves instead of sound waves. Radio waves travel at the
speed of light, about 300,000 kilometers in one second. A radar set sends out a
short burst of radian waves. Then it receives the echoes produced when the
waves bounce off objects. By determining the time it takes for the echoes to
return to the radar set, a trained technician can determine the distance
between the radar set and other objects. The word “radar,” in fact, gets its
name from the term “radio detection and ranging.” Ranging is the term for
detection of the distance between an object and the radar set. Besides being of
critical importance to pilots, radar is essential for air traffic control,
tracking ships at sea, and for tracking weather systems and storms.
1.
What is the main topic of this passage
a.
The nature of radar
b.
Types of ranging
c.
Alternatives to radar
d.
History of radar
2.
In line 1, the word “dense” could be replaced by
a.
Cold
b.
Wet
c.
Dark
d.
Thick
3.
According to the passage, what can radar detect
besides location of objects?
a.
Size
b.
Weight
c.
Speed
d.
Shape
4.
The word “shouts” in line 4 is most similar in
meaning to which of the following?
a.
Eavesdrops
b.
Yells
c.
Confesses
d.
Whispers
5.
Which of the following words best describes the
tone of this passage?
a.
Argumentative
b.
Imaginative
c.
Explanatory
d.
Humorous
6.
The phrase “a burst” in line 7 is closest in
meaning in which of the following?
a.
An attachment
b.
A discharge
c.
A stream
d.
A ray
7.
The word “it” in line 7 refers to which of the
following?
a.
A radar set
b.
A short burst
c.
A radian wave
d.
Light
8.
Which of the following could best replace the
word “bounce” in line 8?
a.
Overturn
b.
Groove
c.
Extend
d.
Rebound
9.
Which type of waves does radar use?
a.
Sound
b.
Heat
c.
Radio
d.
Light
10.
The word “tracking” in line 12 is closest in
meaning to which of the following?
a.
Repairing
b.
Searching for
c.
Glancing at
d.
Fighting
11.
Which of the following would most likely be the
topic of the next paragraph?
a.
Other uses of radar
b.
Uses of sonar technology
c.
Other technology used by pilots
d.
A history of flying
12.
What might be inferred about radar?
a.
It takes the place of a radio
b.
It gave birth to the invention of the airplane
c.
It developed from as study of sound waves.
d.
It has improved navigational safety.
Answer:
1.
A
2.
D
3.
C
4.
B
5.
C
6.
B
7.
A
8.
D
9.
C
10.
B
11.
A
12.
D
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