更多"[不定项选择题]共用题干
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[不定项选择题]共用题干
Less Is More
It sounds all wrong—drilling holes in a piece of wood to make it more resistant to knocks. But it works because the energy from the blow gets distributed throughout the wood rather than fo-
cusing on one weak spot. The discovery should lead to more effective and lighter packaging mate-rials.
Carpenters have known______(51)centuries that some woods are tougher than others. Hickory,for example,was turned into axe handles and cartwheel spokes because it can absorb shocks without breaking. White oak,for example,is much more easily damaued,________(52)it is almost as dense.Julian Vincent at Bathe University and his team were convinced the wood's internal structure could explain the differences.
Many trees have tubular vessels that run_______(53)the trunk and carry water to the leav- es .In oak they are large,and arranged in narrow bands,but in hickory they are smaller,and more evenly distributed.The researchers________(54)this layout might distribute a blow's en-ergy throughout the wood, soaking up a bigger hit.To test the idea,they drilled holes 0.65 millimetres across into a block of spruce,a wood with_______(55)vessels,and found that_______(56)withstood a harder knock_______（57)when there were more than about 30 holes per square centimeter did the wood's performance drop off.
A uniform substance doesn't cope well with knocks because only a small proportion of the material is actually______( 58).All the energy from the blow goes towards breaking the material in one or two places , but often the pieces left _________( 59 ) are pristine（未经破坏的）.
But instead of the energy being concentrated in one place,the holes provide many weak spots that all absorb energy as they break,says Vincent.“You are controlling the places______(60) the wood breaks,and it can then absorb more______(61),more safely.”
The researchers believe the principle could be applied to any material—_________(62)example,to manufacture lighter and more protective packaging.It could_______(63)be used in car bumpers,crash barriers and armor for military vehicles,says Ulrike Wegst,_______(64) the Max Plank Institute for Mental Research in Stuttgart. But she emphasizes that you'd ________(65)to design the substance with the direction of force in mind.“The direction of loading is crucial,”she says.
65._________
A.necessity
B.must
C.need
D.had
[不定项选择题]共用题干
Less Is More
It sounds all wrong一drilling holes in a piece of wood to make it more resistant to
knocks.But it works because the energy from the blow gets distributed throughout the wood
rather than focusing on one weak spot.The discovery should lead to more effective and
lighter packaging materials.
Carpenters have known_________(1)centuries that some woods are tougher than
others. Hickory (山核桃木）,for example, was turned into axe handles and cartwheel
spokes（轮辐）because it can absorb shocks without breaking.White oak,for example,
is much more easily damaged,_________(2)it is almost as dense.Julian Vincent at
Bathe University and his team were convinced the wood's internal structure could explain the
differences.
Many trees have tubular（管的）vessels that run_________(3) the trunk and carry
water to the leaves.In oak they are large,and arranged in narrow bands,but in hickory
they are smaller, and more evenly distributed.The researchers_______(4)this
layout might distribute a blow's energy throughout the wood,soaking up a bigger hit.To
test the idea , they drilled holes 0._________(0.) 65 millimetres across into a block of spruce（云杉）,a
wood with_________(5)vessels,and found that________(6)with stood a harder
knock.__________(7)when there were more than about 30 holes per square centimetre
did the wood's performance drop off.
A uniform substance doesn't cope well with knocks because only a small proportion of
the material is actually_________(8).All the energy from the blow goes towards breaking
the material in one or two places,but often the pieces left_________(9)are pristine（未
经破坏的）.
But instead of the energy being concentrated in one place,the holes provide many
weak spots that all absorb energy as they break,says Vincent. "You are controlling the
places_________(10)the wood breaks,and it can then absorb more__________(11),
more safely."
The researchers believe the principle could be applied to any material一______(12)
example,to manufacture lighter and more protective packaging.It could__________(13)
be used in car bumpers,crash barriers and armour for military vehicles,says Ulrike
Wegst,_________(14)the Max Plank Institute for Mental Research in Stuttgart.But she
emphasizes that you________(15)to design the substance with the direction of force in
mind."The direction of loading is crucial,"she says.
_________(11)
A.water
B.air
C.energy
D.safety
