草桥:在秘鲁阿普玛克河一带的印第安人,喜欢用一种草来架桥。每年雨季,这一带的依素草长得十分茂盛,人们用它拧成绳索,只需几天时间便能架起一座牢固的桥,这种桥可使用两年。纸桥:美国科学家研制出一种奇特的纸桥。桥跨径15米,宽3米,能通过3吨重的汽车。它是用一种新型纸建造的,这种纸里面混有金属丝纤维,强度极高。 Caochangdi: Indians in the Peruvian area of ​​the Appugu River love to bridge with a kind of grass. Every year during the rainy season, this area of ​​grass is very prosperous, people use it to twist the rope, just a few days will be able to set up a solid bridge, this bridge can be used for two years. Paper Bridge: American scientists developed a peculiar paper bridge. Bridge span 15 meters, 3 meters wide, can pass 3 tons of heavy vehicles. It is made of a new type of paper, which is mixed with metal fibers and is extremely strong.