48 Which of the following descriptions of glaciers is true?
(A) Glaciers are the main water source for the Nile.
(B) Melting glaciers may help hydroelectric dams run at maximum power for a long time.
(C) As temperature increases, glaciers are getting built up.
(D) Melting glaciers will result in the decline of sea levels.

The melting waters of the Ruwenzori Mountains feed the headwaters of the Nile. Here, for hundreds of thousands of years, people have depended on the river for basic necessities: water, transportation, farming, and fishing. Now, the glaciers冰川，冰河 of the Ruwenzori are melting so rapidly that they will soon disappear.

Within the next twenty or thirty years, most glaciers冰川，冰河 in Africa and South America will vanish completely. The shrink變小, （使）縮小 of the world’s glaciers冰川，冰河 will have massive巨大的；大量 consequences for community社區；群體 that depend on ice melt.

In the short-term, these consequences may appear beneficial. For example, extra water from glaciers冰川，冰河 means that hydroelectric水力發電 dams will run at maximum power.

In the long run, however, the melting of earth’s glaciers冰川，冰河 could be catastrophe翻譯：大災難；大災禍. 

Today’s extra hydroelectric水力發電 power has been stolen from the future. Communities with ample足夠的，充足 power now may have none after the glaciers冰川，冰河 have melted, and the loss of ice will increase sea levels worldwide.

Temperature change and a lack of snow is causing the retreat退卻；撤退 of the glaciers冰川，冰河. 

Glaciers冰川，冰河 are no longer getting built up during the snowy winter months, so they are no longer able to maintain their size over the long run.

Unless there are some changes in the current rate of global warming, the glaciers冰川，冰河 are essentially doomed註定失敗（或滅亡、毀滅）.

本文主旨在第一句

The melting waters of the Ruwenzori Mountains feed the headwaters of the Nile. Here, for hundreds of thousands of years, people have depended on the river for basic necessities: water, transportation, farming, and fishing.

因此選D