EF Set Aswers 2024

Passage A
Hanging clear, water-filled bags from doorways is an increasingly popular, and

rather unlikely, new method for deflecting annoying and potentially
disease-carrying—flies from building entrances.
Some advocates claim that the flies recognize the liquid as the surface of a
body of water while others—ludicrously—insist the insect flies away because
it is frightened by its own magnified reflection. The most credible explanation,
however, concerns the refraction of light.
Light rays travel in a straight line. Refraction is what happens when something
like a clear object such as a piece of glass or a bag of water-gets in the way.
Hitting the object changes the ray's velocity and direction, bending, or
refracting, it. Refracted rays of light can cause optical illusions, including such
things as mirages that even confuse human eyes.
A fly's head consists primarily of a pair of large complex eyes, each composed
of 3,000 to 6,000 simple eyes. This physiology allows the fly to see in multiple
directions at once. Even though these eyes cannot move or focus on objects
like human eyes, they grant the fly a mosaic view of its surroundings, and
each simple eye provides one small piece of the puzzle. A housefly bases its
sense of direction on the direction sunlight comes from, so when these
complex, sensitive eyes experience refracted light, the fly becomes confused
and flies away.
Although this explanation is persuasive and plausible, research conducted to

replicate the results on fly-plagued poultry farms has been inconclusive.
Passage B
While the water-bag method of fly repellent has many supporters, it has at
least as many detractors. Advocates claim that refracted light in water baffles
the flies' compound eyes. This theory seems quite plausible, but critics
classify it as a kind of coincidence masquerading as cause and effect. They
say that hanging water bags may seem to work due to the placebo effect. In
medicine this is a treatment without therapeutic value, which is administered
as if it were a therapy. The "medicine" makes people feel better due to
psychological effects rather than due to its curative values. The same effect is
likely to occur when people think they are treating a pest problem, and thus
notice that the problem seems to diminish.
But what if the placebo even increases the problem? Recently, scientists
conducted an experiment over the course of thirteen weeks on two egg farms
to measure fly activity and encountered just such a situation. They installed
commercial, water-based optical fly repellents and concluded that the areas
equipped with water bags actually attracted more of these irritating creatures.
Since there are reasonable explanations that support the water-bag method
and significant evidence that argues against it, it's up to you whether you keep
hanging up water-filled bags around your home or not.
1. The passage mentions experiments conducted in an agricultural

environment.
Passage A
Passage B
Both Passages
Neither Passage
2. The passage makes a convincing case for the effectiveness of the

water-bag method.
Passage A
Passage B
Both Passages
Neither Passage
3. The passage states that there are more people who do not believe in the
water-bag theory than there are supporters of the theory.
Passage A
Passage B
Both Passages
Neither Passage
4. The passage suggests that people hang water bags and then notice fewer
pests.
Passage A
Passage B
Both Passages
Neither Passage
5. The author supports the theory that flies are scared of their own reflection.
Passage A
Passage B
Both Passages
Neither Passage
6. The passage mentions the claim that water bags make flies look bigger.
Passage A
Passage B
Both Passages
Neither Passage
7. The passage mentions the fact that flies have compound eyes.
Passage A
Passage B
Both Passages
Neither Passage
8. The passage states that use of water bags is connected to higher levels of
fly activity.
Passage A
Passage B
Both Passages
Neither Passage
9. The passage claims that refracted light can affect human optical
perceptions.
Passage A
Passage B
Both Passages
Neither Passage
10. The passage mentions the claim that refracted light in water confuses
flies.
Passage A
Passage B
Both Passages
Neither Passage
11. The author of the passage dismisses the water-bag method as ineffective.
Passage A
Passage B
Both Passages
Neither Passage
12. The author of the passage cites human beliefs as an explanation.
Passage A
Passage B
Both Passages
Neither Passage

EF Set Aswers 2024

Uploaded by

EF Set Aswers 2024

Uploaded by

Passage A

Hanging clear, water-filled bags from doorways is an increasingly popular, and

Although this explanation is persuasive and plausible, research conducted to

1. The passage mentions experiments conducted in an agricultural

2. The passage makes a convincing case for the effectiveness of the

12. The author of the passage cites human beliefs as an explanation.

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