In the Beijing Winter Olympics，we were treated to incredible displays of athletic talents as competitors took to the snow and ice.As a popular sport at the Winter Olympics，ski jumping is one of the best examples to showcase the "superhuman" power of athletes.
Ski jumpers soar into the air and appear to be almost flying in the sky.How do they achieve this？Physics call offer us an explanation of how they make it.It involves the use of the laws of aerodynamics（空氣動力學）to fight against gravity and increase lift while reducing drag.
To understand how ski jumping works，we need to consider three elements：gravity，lift and drag.Gravity is the force that pulls us towards an object.Lift occurs when an object is moving through the air—as its surface comes into contact with air particles（微粒），the particles are pushed down and away from the object，allowing it to move up.At the same time，this Interaction creates drag，and slows down an object's movement.
While there is nothing that the skiers can do about gravity，they can twist their bodies into positions that allow them to achieve greater lift and avoid as much drag as possible.According to the Smithsonian Magazine， "To do this，athletes try their best to make their skis and body nearly parallel to the ground and place their skis in a V-shape just outside the form of the body，This position increases the surface area that produces lift and puts them in the ideal angle that will also maximize（最大化）lift."
Because of how the sport works，athletes' equipment is strictly controlled according to weight and height in order to avoid any unfair advantages.This means suits must be tight in order to ensure athletes cannot use them as a way to gain more lift.For athletes，minor day-to-day water weight changes as little as 300 grams.It can mean that suits will not be tight enough according to their body mass indexes（體重指數）.
（1）What does the underlined word "It" refer to in the second paragraph？ AA
A．Ski jumping.
B．Athletic talent.
C．Physical science.
D．Superhuman power.
（2）What contributes to lift in ski jumping？ DD
A．The interaction between force and drag.
B．The interaction between gravity and balance.
C．The interaction between air particles and gravity.
D．The interaction between skiers and air particles.
（3）What should ski jumpers do in order to achieve the best performance？ AA
a.Keep their bodies and skis parallel to the ground.
b.Change their positions as little as possible.
c.Position their skis in a V-shape when they jump.
d.Increase the angle as much as possible.
A．ac
B．bc
C．cd
D．ad
（4）What is required to ensure fair play in ski jumping？ CC
A．Specially made suits.
B．Strict control of athletes' height.
C．Standardized equipment.
D．Much daily water intake.
（5）What's the main focus of the text？ BB
A．The techniques used by ski jumpers.
B．The scientific principles behind ski jumping.
C．Rules of the ski jumping competition.
D．Excellent performances in ski jumping.
【答案】A；D；A；C；B
【解答】
【點評】
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發(fā)布：2024/4/20 14:35:0組卷：9引用：3難度：0.5
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G．But reading to children does more than create warm memories．發(fā)布：2025/1/1 13:30:1組卷：14引用：7難度：0.7 -
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D．A textbook.發(fā)布：2025/1/1 16:0:1組卷：21引用：4難度：0.5 -
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C．physical appearance
D．family relationship發(fā)布：2025/1/1 16:0:1組卷：0難度：0.5