首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
It sounds all wrong-drilling holes in a piece of wood to make it more resistant to knock. But it works because the energy from t
It sounds all wrong-drilling holes in a piece of wood to make it more resistant to knock. But it works because the energy from t
admin
2011-01-05
32
问题
It sounds all wrong-drilling holes in a piece of wood to make it more resistant to knock. 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 (51) centuries that some woods are tougher than others. Hickory(山核桃木), for example, was turned into axe handles and cartwheel spokes (车轮辐条) because it can absorb shocks without breaking. White oak (橡木), for example, is much more easily damaged, (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(管状的) vessels that run (53) 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 (54) this layout might distribute a blow’s energy throughout the wood, soaking up a bigger hit. To test the idea, they drilled holes 0.65 millimeters across into a block of spruce(云杉), 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. That could (63) be used in car bumpers (保险杠), 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.
选项
A、necessity
B、must
C、need
D、had
答案
C
解析
本题考查的是动词的用法。“you’d中的’d=would,后面应跟原形动词:must是情态动词,只有need符合题意,可以跟不定式短语(need也可以作情态动词,但此处不是)。故选C。
转载请注明原文地址:https://kaotiyun.com/show/V9Qd777K
本试题收录于:
职称英语理工类C级题库职称英语分类
0
职称英语理工类C级
职称英语
相关试题推荐
Common-coldSenseYoucan’tbeatit,butyoudon’thavetojoinit.Maybeitgotthename"commoncold"becauseit’smorec
Practicallyallanimalscommunicatethroughsounds.
NaturalMedicinesSinceearliestdays,humanshaveusedsomekindsofmedicines.Weknowthisbecausehumanshavesurvived.A
InitiallythewriterdidnotwanttobuyahearingaidbecauseAccordingtothepassage,hearinglossis
InitiallythewriterdidnotwanttobuyahearingaidbecauseOnespecialfeatureofCrystalEaristhat
InitiallythewriterdidnotwanttobuyahearingaidbecauseWhichofthefollowingisNOTtrueofCrystalEar?
Herjudgementiswarped,biasedbecauseofpossibleadvantageforherself.
Themachineisunsafebecauseofthedefectsinit.
Theauthor’sprimarypurposeis______。Itcanbeinferredthatdoctorsareabletodeterminehospitalpoliciesbecause______.
1.Medicineisthescienceandartofhealing.Itisasciencebecauseitisbasedonknowledgegainedthroughcarefulstudyand
随机试题
回火是将淬火钢加热到________某一温度,保温一定时间,然后冷却至室温的热处理工艺。
铁壳刀开关的常用型号有()。
管道系统试验的类型主要包括()试验。
招标人根据工程实际情况需要修改合同条款的内容,可以在()进行修改。
甲企业2010年取得了国库券投资的利息30000元,其他公司债券投资利息70000元,全年税前利润为690000元,所得税税率为25%。若无其他纳税调整项目,则2010年该企业的净利润为()元。
入住通知书、入住须知、用户手册、管理公约等是()。
遏制“屡教不改”,需要从多方面人手。对一再重犯的问题企业,不能简单地整改了事,要对相关负责人依法依规问责,纪委、监察、司法、公安等部门都要依法介入。有的企业是“你审你的计,我犯我的规”,甚至怀揣着“犯了再改、改了又犯”的心态,如果仅仅“罚酒三杯”,相关负责
假释的考验期限,从()起计算。
某实验室需购某种化工原料106千克,现在市场上该原料有两种包装,一种是每袋35千克,价格为140元;另一种是每袋24千克,价格为120元。在满足需要的条件下,最少要花费()元
在Internet中,不需运行IP协议的设备是()。
最新回复
(
0
)