17.What is this passage mainly about?
(A)Antarctic tourism and its possible effects on the environment.
(B)The influence of modern technology on historic sites.
(C)A cool trip to the Antarctic wilderness.
(D)Cruise liners and marine pollutants.

A century ago, distance路程 and extreme極端 cold meant意味、打算(mean的過去式) that Antarctica南極 was only a place for explorers探險者.

Modern technology has changed all that. 

Now cruise liners大型遊輪 with up to a thousand passengers travel through the Antarctic waters. 

Only in the last decade has the Antarctic tourist trade貿易 taken off開啟.

In the early 90s九十年代 about 5,000 tourists a year travelled to Antarctica.

Last year, there were more than 28,000 visitors, and if the growth continues at the same rate it could be up to 80,000 by 2010.

Tourists that set foot on Antarctica are concentrated集中 in biologically生物 rich sites, and historic or current sites of human activity. 

Tourism旅遊業 is focused on sites known for fantastic wildlife and stunning scenery景色. 

The impact of these routine tourism operations is not yet well known眾所周知, though industry claims要求、宣稱 that there has been no impact衝擊 from several decades of tourism. Achieving實現 a balance between tourism and managing管理 the pristine嶄新 wilderness荒野 is worrying environmentalists環境保護主義者.

They are concerned not just by the rising number of tourists but by the changing nature of Antarctic tourism. 

Large cruise liners大型遊輪 run by global companies公司 are now entering the Antarctic tourist trade, marking the beginning of mass大量 tourism in Antarctica. 

They also carry huge quantities of heavy oil, one of the worst marine pollutants. 

“The effects of one liner郵輪 sinking沈沒 or running aground would be disastrous災難性的,” says an environmentalist. 

While the environmental impact of fifty tourists turning up出現at a penguin colony群聚區 or historic hut小屋 may be minimal極小, 800 to 1,000 is a different story.