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【单选题】

第二篇
Pushbike Peril
Low speed bicycle crashes can badly injure—or even kill—children if they fall onto the ends of the handlebars (车把). So a team of engineers is redesigning the humble handlebar in a bid to make it safer.
Kristy Arbogast, a bioengineer at the Children’s Hospital of Philadelphia in Pennsylvania, began the project with her colleagues after a study of serious abdominal (腹部的) injuries in children in the past 30 years showed that more than a third were ca,used by bicycle accidents. "The task was to identify how the injuries occurred and come up with some countermeasures (对策)", she says.
By interviewing the Children and their parents, Arbogast and her team were able to reconstruct (重建;重构) many of the accidents and identified a common mechanism responsible for serious injures. They discovered that most occur when children hit an obstacle at a slow speed, causing them to topple over. To maintain their balance they turn the handlebars, through 90 degrees — but their momentum (冲力) forces them into the end of the handlebars. The bike then falls over and the other end of the handlebars hits the ground, ramming it into their abdomen.
The solution the group came up with is a handgrip(握柄) fitted with a spring and damping (制动的;减速的,缓冲的) system. The spring absorbs up to 50 percent of the forces transmitted through the handlebars in an impact. The group hopes to commercialize (使商品化) the device, which should add only a few dollars to the cost of a bike. "But our task has been one of education because up until now, bicycle manufacturer were unaware of the problem," says Arbogast.
The team has also approached the US Consumer Product Safety Commission to try to persuade man-ufacturers to adopt the new design. A decision is expected later this year.
The passage implies that

A.
it is not easy to persuade manufacturers to adopt the new design.
B.
the team of engineers has not found any countermeasures.
C.
children like to ride bicycles at a very low speed.
D.
a lot of children were killed in bicycle accidents in the past 30 years.
题目标签:重构商品化冲力
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【单选题】第二篇 Pushbike Peril Low speed bicycle crashes can badly injure—or even kill—children if they fall onto the ends of the handlebars (车把). So a team of engineers is redesigning the humble h...

A.
it is not easy to persuade manufacturers to adopt the new design.
B.
the team of engineers has not found any countermeasures.
C.
children like to ride bicycles at a very low speed.
D.
a lot of children were killed in bicycle accidents in the past 30 years.

【单选题】(2005年)要用冲床在厚度为t的钢板上冲出一圆孔,则冲力大小( )。

A.
与圆孔直径的平方成正比
B.
与圆孔直径的平方根成正比
C.
与圆孔直径成正比
D.
与圆孔直径的三次方成正比

【单选题】商品化育苗采用的基质材料是( )。

A.
草炭、珍珠岩、蛭石
B.
草炭、沙土、蛭石
C.
草炭、壤土、蛭石
D.
草木灰、珍珠岩、蛭石