2．
The webs that spiders build to catch insects seem weak．However，the strength of spider thread is greater than steel．Webs can even stand up to very strong storms．
Now a team，headed by Markus Buehler，a scientist at the Massachusetts Institute of Technology，has worked out why the spider web is so strong．It is not just the strength of the thread，but the clever design of the web．The key to a web's success is its ability to keep its shape and strength even after some of the threads break，says Buehler．The scientists found the thread itself has the ability to become softer or firmer．So it can hold different types of heavy things and bear a localized damage （損壞）．This localized damage can simply be repaired，rather than replaced，or even left alone if the web continues to work as before．
Buehler's research is mostly theoretical （理論上的），based on computer modeling of material properties （特性） and how they respond to stresses．But in order to test the findings，he and his team literally went into the field．They tested actual spider webs by poking and pulling at them．In all cases，damage was limited to the immediate area they disturbed．
In tests，scientists also used three other strong materials made into the same webs．The spider thread was six times stronger than any other material．More surprisingly，when the scientists took away up to 10percent of the threads from different places，the web didn't become any weaker．Actually，it became up to 10 percent stronger．
The spider web's clever design gives scientists many new ideas．The findings might be used not just for physical objects such as safer buildings，but also in the design of networked systems．For example，a computer experiencing a virus attack could be designed to shut down at once，before its problems get worse．"It's a really good chance，"said Buehler．"It may give us some new ideas for engineering．"
56．Where does the strength of the web threads come from？D
A．Their high stickiness．
B．Their high firmness．
C．Their clever design．
D．Their ability to change in quality．
57．Which word is closest in meaning to the word"disturb"in the 3
rd paragraph？A
A．Upsetting．
B．Changing．
C．Moving．
D．Hitting．
58．How many different experiments did Buehler's team do to test their findings？C
A．One．
B．Two．
C．Three．
D．Four．
59．What can be the best title for the passage？B
A．Spider Webs Are Stronger than Steel
B．Spider Webs Hold Valuable Secrets
C．How Spider Webs Get Their Strength
D．What Strong Spider Webs Mean to Us．
學期復習一本通學習總動員期末加暑假延邊人民出版社系列答案
