用方框中所给词的适当形式填空。使文章通顺,连贯。合理。（每空一词。每词限用一次）

fall       turn to         with         high         little         explore         cover         those

    The Antarctic is actually a desert. It is the only continent on the earth  a river or a lake. The Antarctic is  with ice all the year round. The  temperature ever recorded there is zero at South Pole.  used to think that a place so cold would have a heavy snow­fall. But less than ten inches of snow falls there each year. That is less than half an inch of water. It's even much  than  of Sahara. The little snow that  in Antarctica never becomes water. It continues to pile up deeper and deeper year after year and century after centu­ry. When the snow gets to be about eighty feet deep, it will be  ice by the weight of the snow above it.