TOEFL Reading練習 #001 — The Quicksand That Won't Swallow You(日本語解説)

1. A. very frightening
2. B. very rare
3. C. very old
4. D. very useful

1. A. the underground spring
2. B. the grains
3. C. liquefaction
4. D. a rising tide

1. A. the process of a gas cooling down until it becomes a liquid
2. B. the change of packed, wet sand into a liquid-like mixture once its grains stop pressing against each other
3. C. the weight of a footstep pressing down on top of dry sand
4. D. the packing of loose sand grains into a solid, sand-castle-like block

1. A. Because the grains are unusually smooth and slide past each other easily
2. B. Because water fills the gaps between the grains and pushes them apart
3. C. Because footsteps grind the grains down into smaller pieces
4. D. Because the tide carries the sand grains away entirely

1. A. Its reputation for danger is scarier than how it actually behaves
2. B. In movies, a person is shown sinking until only a hand is left above the surface
3. C. It can be found in many different kinds of dry environments
4. D. It forms when sand and water combine in a particular way

1. A. Liquefied sand resists more than water does, so a sinking body stops around waist level once the forces balance.
2. B. Sand and water push back with exactly the same force, so people always sink down to the waist.
3. C. A person's body pushes against the sand until it reaches waist level, and this is what turns the sand into a liquid.
4. D. Liquefied sand pushes back harder than water only when a person struggles, stopping the sinking exactly at the knees.

1. A. The water in the Dead Sea likely pushes back harder against a floating body than ordinary pool water does
2. B. The Dead Sea is warmer than an ordinary pool, which helps swimmers float
3. C. The passage states that the Dead Sea contains large amounts of sand
4. D. Swimmers actually float less easily in the Dead Sea once their body reaches waist level

1. A. explain how a person can escape from quicksand safely
2. B. give scientific support for the density-based explanation given earlier in the paragraph
3. C. compare quicksand and the Dead Sea in full detail
4. D. describe how rising tides raise water levels

1. A. It argues that the explanation given in paragraph 3 is incorrect
2. B. It repeats the 2005 study from paragraph 3 in more detail
3. C. It introduces a completely different cause of quicksand formation
4. D. It shifts from why a person cannot sink completely to what the real danger of quicksand actually is

1. A. Square A
2. B. Square B
3. C. Square C
4. D. Square D

Quicksand forms through a process called liquefaction, but a person cannot sink into it completely because of a difference in density.

1. A. In movies, a person who steps into quicksand is often shown sinking completely out of sight.
2. B. Quicksand forms when water fills the gaps between sand grains and pushes them apart, turning the packed sand into a liquid-like mixture.
3. C. Because quicksand is denser than a human body, a sinking person stops at a balance point, usually around the waist.
4. D. In 2005, a team of physicists tested the density pattern by shaking sand and water together in a lab.
5. E. Struggling in quicksand makes escape harder, while staying calm and moving slowly usually frees a stuck leg.
6. F. Quicksand can only form in deserts where there is little rainfall.