When timber has been purchased on a （"per unit of volume") harvested basis, the losses ass

a fifth of the world's fresh water reserves. It is a precious resource, an area of surpassing beauty and to some extent, the very symbol of our nation. For several years, newspapers had been publishing Manning reports on threats to Baikal from industrial construction along its shores, the felling and rafting of timber and pulp mill's discharge of chemical wastes.

Documents revealed that Orlov, the prime minister in charge of the paper industry, had ordered construction of a large cellulose complex on the lake's shores to produce a particularly durable rayon cord for airplane tires with the assumption that the pure water would facilitate the chemical process resulting in stronger fibers, and the story goes that Orlov had chosen the site by simply pointing to a place on the shoreline while cruising in a motorboat with some old friends. Tile site, however, turned out to be a seismically active region, and the buildings, while supported by steel piles, are still vulnerable to the major earthquakes that have occurred there once or twice a century.

The pure water helped the process, whose final product proved out-of-date, aviation industry switching to metallic cord. The variety of fish, unfortunately, fell victim to the toxic waste, the fragile ecological balance of the region threatened. Those concerned proposed that the lakeshores be closed to new industry and existing enterprises be moved but they encountered tough resistance from officials defending their decision and saving face by insisting on the complex's importance. Of course, what you see on pictures is still a beauty but the lake is no longer a home to more than 1,000 species of plants and animals unknown anywhere else.

The statement that best relates the main idea of this passage is ______.

A．too many people are attracted to the lake that it has now been deprived of its natural beauty

B．an important natural resource is destroyed by human ignorance

C．industry is less important than ecological balance

D．one should be extremely careful when choosing a construction site

A.have

B.is

C.does

D.has

_____, water turns into ice.

A、When freezing

B、When frozen

C、When it has been frozen

D、When freezes to it

The meeting _____when Mr. Wang _____to school.

A、has begun; get

B、has been on; get

C、had begun; got

D、had been on; got

It has been years __________ I returned home.

[A]after

[B]that

[C]since

[D]when

A.has begun

B.had begun

C.had been on

D.has been on

A.when

B.before

C.while

D.since