Less Is More

It sounds allwrong-drilling holes in a piece of wood to make it more resistant to knocks.Butit works because the energy from the blow gets distributed throughout the wood

rather than focusingon one weak spot.The discovery should lead to more effective and lighterpackaging materials.Carpenters have known______(51) centuries that some

woods are tougherthan others.Hickory（山核桃木）,forexample, was turned into axe handles and cartwheel spokes（轮辐）because it can absorb shocks without breaking.

White oak,forexample,is much more easily damaged,______(52)it is almost as dense.JulianVincent at Bathe University and his team were convinced that the wood'sinternal

structure couldexplain the differences. Many trees have tubular（管状的）vessels that run _______(53) the trunk and carrywater to the leaves.In oak they are large,and

arranged in narrowbands,but in hickory they are smaller,and more

evenlydistributed.The researchers_______(54)this layout might distribute a blow'senergy throughout the wood,soaking up a bigger hit.To test the idea,theydrilled holes 0.65

millimetres acrossinto a block of spruce（云杉）,awood with ________( 55 ) vessels , and found that______( 56 ) withstood aharder knock.______(57)when there were

more than about 30holes per square centimetre did the wood's performance drop off. A uniform substancedoesn't cope well with knocks because only a small proportion of

the material isactually______(58).All the energy from the blow goes towards breaking thematerial in one or two places , but often the pieces left ______（59 ) are pristine

（未经破坏的）.

But instead of theenergy being concentrated in one place,the holes provide many weak spots thatall absorb energy as they break,says Vincent."You are controlling the

places_______(60)thewood breaks,and it can then absorb more______(61),more safely."The researchersbelieve the principle could be applied to any material________(62)

example,tomanufacture lighter and more protective packaging.It could_______(63)be used incar bumpers,crash barriers and armour for military vehicles,says Ulrike

Wegst,a_______(64)atthe Max Plank Institute for Mental Research in Stuttgart.

But she emphasizesthat you______(65)to design the substance with the direction of force in mind."The direction of loading is crucial,"she says.59._________

A.behind

B.beyond

C.for

D.in