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 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 0.65 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. in B. since C. for D. at

Another (2) that she was late for a Monday class because she was recovering from drinking too much at a wild weekend party.At colleges and universities in the US, e-mail has made professors more approachable (平易近人). But many say it has made them too accessible, (3) boundaries that traditionally kept students at a healthy distance.
These days, professors say, students seem to view them as available (4) the clock, sending a steady stream of informal e-mails.
"The tone that they take in e-mails is pretty astounding (令人吃惊的) ," said Michael Kessler, an assistant dean at Georgetown University. "They’ll (5) you to help: ’I need to know this. ’"
"There’s a fine (6) between meeting their needs and at the same time maintaining a level of legitimacy (正统性) as an (7) who is in charge. "
Christopher Dede, a professor at the Harvard Graduate School of Education, said (8) show that students no longer defer to (听众) their professors, perhaps because they realize that professors’ (9) could rapidly become outdated.
"The deference was driven by the (10) that professors were all-knowing sources of deep knowledge," Dede said, and that notion has (11) .
For junior faculty members, e-mails bring new tension into their work, some say, as they struggle with how to (12) . Their job prospects, they realize, may rest in part on student evaluations of their accessibility.
College students say e-mail makes (13) easier to ask questions and helps them learn.
But they seem unaware that what they write in e-mails could have negative effects (14) them, said Alexandra Lahav, an associate professor of Law at the University of Connecticut.
She recalled an e-mail message from a student saying that he planned to miss class so he could play with his son. Professor Lahav did not respond.
"Such e-mails can have consequences," she said. "Students don’t understand that (15) they say in e-mail can make them seem unprofessional, and could result in a bad recommendation. \