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【单选题】

美国薄壳山核桃适宜种植海拔是()米之间

A.
800
B.
900
C.
1000
D.
800—1700
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参考答案:
参考解析:
.
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【单选题】适宜种植茶苗的环境有()。

A.
土壤干燥
B.
土层薄
C.
烈日
D.
透气良好

【单选题】下列适宜种植小麦和甜菜的地区是[ ]

A.
东北平原
B.
华北平原
C.
成都平原
D.
长江中下游平原

【单选题】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 ...

A.
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).
B.
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. "
C.
The researchers believe the principle could be applied to any material- (12) example, to manufacture lighter and more protective packaging. It could (13) be used in car bumpers, crash barriers and arm our 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.