[单项选择]Mostocean waves are generatedby wind current that agitate the water's surface.

[单项选择]The power produced by the waves, tide and wind ______.
A. is not as consistent as it should be
B. is generally less in winter than in summer
C. is never likely to be very great
D. is consistent

[单项选择]Waves generally result from wind ______ on water.
A. acts
B. to act
C. it acts
D. acting

[单项选择]What important discovery about seismic waves does the instructor mention

[单项选择]Ocean waves can cut imposing cliffs along coastlines.（）
A. immobile
B. impermeable
C. impressive
D. imaginative

[单项选择]Initial reports were that multiple waves of warplanes bombed central Baghdad, hitting oil refineries and the airport.
A. beating
B. knocking
C. hurting
D. striking

[单项选择]Seismic waves generated by an earthquake or large explosion can be recorded thousands of kilometer from their source.

[单项选择]

Very high waves are destructive when they strike the land. Fortunately, this seldom happens. One reason is that out at sea, waves moving in one direction almost always run into waves moving in a different direction. The two sets of waves tend to cancel each other out. Another reason is that water is shallower near the shore. As a wave gets closer to land, the shallow bottom helps reduce its strength.
But the power of waves striking the shore can still be very great. During a winter gale, 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 raging storms, the water a hundred fathoms (600 feet) beneath the surface is just as calm as on a day without a breath of wind.

From the second paragraph of th
A. constant
B. equalized
C. variable
D. perpetual

[单项选择]The prevailing wind is the wind direction most often observed during a given time period. Wind speed is the rate at which the air moves past a stationary object.
A. motionless
B. massive
C. flexible
D. noticeable