[单项选择]（）into oceans and rivers is a serious form of pollution.
A. Pouring sewage
B. Emptying litter
C. Throwing garbage
D. Dumping sewage

[单项选择]________into oceans and rivers is a serious form of pollution.
A. Pouring sewage
B. Emptying litter
C. Throwing garbage
D. Dumping sewage

[单项选择]Dump sewage into oceans and rivers is a serious form of pollution.（）
A. Having dumped sewage
B. Being dumped sewage
C. Dumped sewage
D. Dumping sewage

[单项选择]The least serious form of brain trauma, characterized by a brief loss of consciousness and period of confusion, is called
A. contusion.
B. concussion.
C. coup.
D. contrecoup.

[单项选择]Found in all oceans thevarious species of electric rays use the charge they can generate for both stunning prey or warding off predators.

[单项选择]

Passage Four
The atmosphere and oceans are not the only parts of the environment being damaged. Rain forests are being quickly destroyed as well, and their survival is questionable. E. O. Wilson, a biologist at Harvard, calls the depletion(枯竭、耗尽)of rain forest areas "the greatest extinction since the end of the age of dinosaurs(恐龙)".
Unlike some environmental issues, ram forest depletion has fortunately received significant public and media attention. Despite the opposition to the cutting down of rain forests, the problem continues. Every year, Brazil chops down on area of forest the size of the state of Nebraska. In addition to the Amazon’s rain forests, many other forests are being cut down as well. In Indonesia, Zaire, Papua New Guinea, Malaysia, Burme, the Philippines peru, Colombia, Bolivia, and Venezuela, rain forests that were once great have been lost.
According to some estimates, 50 million acres of rain forest are cu
A. The United Nations says about 50 million acres of rain forests are cut down every year.
B. Luckily people and mass media all paid special attention to the depletion of rain forests.
C. The author thought the oceans' survival is questionable.
D. People have stopped cutting down rain forests because of the opposition of most peopl

[单项选择]The passage asserts that one reason that oceans become enriched in oxygen-18 as ice sheets grow is because______.


A. water molecules containing oxygen-18 condense and fall as precipitation slightly sooner
B. the ratio of oxygen-18 to oxygen-16 in water vapor evaporated from oceans if different from that of these isotopes in seawater
C. growing ice sheets tend to lose their oxygen-18 as the temperature of the oceans near them gradually decreases
D. less water vapor evaporates from oceans during glacial periods and therefore less oxygen-18 is removed from the seawater

[单项选择]

Text 3
The oceans are the main source of humidity, but plants also pour moisture into the air. In one day, a five - acre forest can release 20, 000 gallons of water, enough to fill an average swimming, pool. A dryer extracts moisture from wet clothes, adding to humidity. Even breathing contributes to this sticky business. Every time we exhale, we expel nearly one pint of moist air into the atmosphere.
Using sophisticated measuring devices, science is learning more and more about the far - reaching and often surprising impact humidity has on all of us.
Two summers ago angry callers phoned American Television and Communications Corp. ’ s cable - TV operation in northeastern Wisconsin, complaining about fuzzy pictures and poor reception. "What happened," said the chief engineer, "was that the humidity was interfering with our signals. "When a blast of dry air invaded the state, the number of complaints dropped sharply.

A. Nowadays science is learning more and more about the impact humidity has on all of us by using sophisticated measuring devices.
B. Humidity could interfere with television signals.
C. Humidity may warp priceless antiques.
D. Visual disturbances may decrease in days of low humidity.