辛达托福代报考位：到2016年7月18日上午托福官网没有释放考位，在此提醒广大考生抓紧时间报名，注意自己的考试时间，如对托福报名有任何疑问，欢迎咨询在线客服

CICADA

Their life cycle takes 17 years in northern species (the so-called 17-year locusts) and 13 years in southern species; the two types overlap in parts of the United States. The female deposits her eggs in slits that she cuts in young twigs. In about six weeks the wingless, scaly larvae, or nymphs, drop from the tree and burrow into the ground, where they remain for 13 or 17 years, feeding on juices sucked from roots.

The nymphs molt periodically as they grow; finally the full-grown nymphs emerge at night, climb tree trunks and fences, and shed their last larval skin. The winged adults, which generally emerge together in large numbers, live for about one week.

Cicada larvae do little damage, but when adults appear in large numbers their egg-laying may damage young trees. Cicadas are sometimes kept for their song in Asia, as they were in ancient Greece.

LICHEN 

usually slow-growing organism of simple structure, composed of a fungus (see Fungi) and a photosynthetic green alga (see algae) or cyanobacteria living together in a symbiotic relationship and resulting in a structure that resembles neither constituent. Lichens commonly grow on rocks, trees, fence posts, and similar objects.

Lichens require no food source other than light, air, and minerals. They depend heavily on rainwater for their minerals and are sensitive to rain-borne pollutants.

Before the discovery of aniline dyes, lichens were much used for silk and wool dyes. Others have been used in perfume manufacturing and brewing.

YELLOWSTONE PARK

the world’s first national park. The area, a huge craterlike volcanic basin, is a geological “hot spot” and the site of several massive eruptions, the most recent occurring 600,000 years ago. The plateau is mostly formed from once-molten lava. Volcanic activity is evidenced by nearly 10,000 hot springs, 200 geysers, and many vents and mud pots. The more prominent geysers are unequaled in size, power, and variety. The park also has petrified forests, lava formations, and the “black glass” Obsidian Cliff.

The park has a wide variety of flowers and other plant life. Bears, mountain sheep, elk, bison, moose, many smaller animals, and more than 200 kinds of birds inhabit Yellowstone, which is one of the world’s largest wildlife sanctuaries. Fires in 1988 burned about 36% of the park, but animal and plant life rebounded quickly, as the nutrient influx in the ash nourished the soil.

大家在进行托福备考的同时，如果对考位方面也比较紧张，可联系辛达代报为您服务