請回答第 42 題至第 45 題：
Real quicksand, the kind that is almost impossible to extricate yourself from, is not just water and sand. A
report in the current issue of Nature shows that salt and clay are also major ingredients.
Their study began when Dr. Daniel Bonn, a professor of physics at the University of Amsterdam, was in Iran
a few years ago and saw signs warning of quicksand. Naturally, the warning prompted him to collect samples and
he sank in to his ankles.
He quickly escaped, but even shallow quicksand can be hard to step out of. Back home, Dr. Bonn and his
colleagues found out why. Sand grains in quicksand are usually loosely packed, with the clay acting as a fragile
gel holding the grains together.
Hit with sudden force from a hapless victim, the quicksand gel turns to liquid. Then salt causes clay particles
to stick to one another instead of the sand grains, with the result that a victim ends up surrounded by densely
packed sand.
The force needed to pull out a person immersed in quicksand is about the same needed to lift a car, Dr. Bonn
said. The trick for escaping is to slowly wiggle the feet and legs, allowing water to flow in. People float in
quicksand so it is also impossible to sink all the way in, but quicksand usually forms at river estuaries, so a
captive could drown at high tide.
【題組】43 Which of the following statements is NOT true?
(A)Dr. Bonn’s experience in Iran initiated his subsequent research on quicksand.
(B)The amount of force necessary to get a trapped foot out of the quicksand is huge.
(C)Dr. Bonn was trapped in the quicksand because he failed to notice the warning sing.
(D)People who sink in quicksand are likely to die from drowning.
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