Icebergs areamong nature's most spectacular（壮观的）creations , and yet most people have never seen one.A vague air ofmystery envelops them.They come into being

somewhere infaraway, frigid waters,amid thunderous noise and splashing turbulence,which inmost case no one hears or sees. They exist only a short time and then slowly

waste away（消融）just as unnoticed.

2. Objects ofsheerest（最纯粹的）beauty theyhave been called. Appearing in an endless vaniety of shapes,they may bedazzlingly white,or they may be glassy blue,green

or purple,tintedfaintly on in darker hues.They are graceful, stately,inspiring in calm,sunlightseas.

3.But they are alsocalled frightening and dangerous,and that they are一in the night,in the fog,and instorms.Even in clear weather one is wise to stay a safe distance away

from them.Most oftheir bulk is hidden below the water,so their underwater parts may extend outfar beyond the visible top.Also,they may roll over unexpectedly,churning the

waters around them.

4.Icebergs are partsof glaciers that break off,drift into the water,float about awhile,and finallymelt.Icebergs afloat today are made of snowflakes that have fallen over long

ages of time.Theyembody snows that drifted down hundreds,or many thousands,or in some casesmaybe a million years ago.The snows fell in polar region and on cold

mountains,where theymelted only a little or not at all,and so collected to great depths over theyears and centuries.As each year's snow accumulation lay on the

surface,evaporationand melting caused the snowflakes slowly to lose their feathery points andbecome tiny grains of ice.When new snow fell on top of the old,it too turned to

icy grains.Soblankets of snow and ice grains mounted layer upon layer and were of such greatthickness that the weight of the upper layers compressed the lower ones.With

time and pressurefrom above, the many small ice grains joined and changed to larger crystals,andeventually the deeper crystals merged into a solid mass of ice.With time andpressure from above,the many small ice grains joined and changed to__________,and eventually the deeper crystals merged into a solid mass of ice.

A.larger than thepart above the water

B.stay near theiceberg

C.melt away just asunnoticed

D.larger crystals

E.stay away fromiceberg