1 . Using his skis, Nicholas built a snow cave. He gathered a huge mass of snow and dug out a hole in the middle. Then he piled branches on top of himself, like a blanket (carpet) , to stay as warm as he could.

How did Nicholas keep himself warm?

A．He found a shelter.	B．He lighted some branches.
C．He kept on skiing.	D．He built a snow cave.

2 . So far, the world has relied on wood, oil, coal, and natural gas to produce energy for heating, lighting, transportation, and manufacturing. Since the 1950s, world consumption has been increasing persistently. In the year 2000, 80 percent of commercial energy was generated from the combustion of fossil fuels, and every day, 50 million barrels of oil are reined (支配) and converted to gasoline and other fuels. In addition to the rapid exhaustion of fossil fuels, the consequences of high consumption rates are pollution and global warming.
How long has the world been in high speed of burning fossil fuel for energy?

A．For half a century.	B．For nearly sixty years.
C．For over 70 years.	D．For more than a century.