Very high waves are destructive when they strike the land. Fortunately, this seldom happen
But the power of waves striking the shore can still be very great. During a winter gale(大风), waves sometimes strike the shore with the force of 6,000 pounds for each square foot. That means a wave, 25 feet high and 500 feet along its face, may strike the shore with a force of 75 million pounds.
Yet the waves, no matter how big or how violent, affect only the surface of the sea. During the most violent storms, the water a hundred fathoms(600 feet) beneath the surface is just as calm as on a day without a breath of wind.
According to the passage, destruction caused by high waves occurs ______.
A.regularly
B.rarely
C.frequently
D.suddenly