共用题干 The Greatest Mystery Of Whales

The whale is a warm-blooded,air-breathing animal,giving birth to its young alive,
sucking them一and,like all mammals,originated on land.There are many_________
(1)of this. Its front flippers（鳍状肢）,used for steering and stability,are traces of feet.
Immense strength is_________(2)into the great body of the big whales,and in
fact most of a whale"s body is one gigantic muscle.The blue whale"s pulling strength has
been estimated_________(3)400 horsepower. One specimen was reported to have
towed（拖）a whaling vessel for seven hours at the_________(4)of eight knots （节）.
An angry whale will_________(5)a ship.A famous example of this was the fate
of whaler Essex,_________(6)was sunk off the coast of South America early in the
last century. More recently,steel ships have_________(7) their plates buckled（使弯
曲）in the same way. Sperm whales（抹香鲸）were known to seize the old-time
whaleboats in their jaws and crush them.
The greatest_________(8)of whales is their diving ability.The sperm whale dives
to the bottom for his_________(9) food, the octopus（章鱼）.In that search he is
known to go as far down as 3, 200 feet,where the_________(10)is 1,400 pounds,to
a square inch.Doing so he will_________(11)underwater long as one hour. Two
special skills are involved in this:storing up enough_________(12)(all whales are air-
breathed)and tolerating the great change in pressure.Just how he does it scientists have
not_________(13).It is believed that some of the oxygen is stored in a special
_________(14)of blood vessels,rather than just held in the lungs.And it is believed
that a special kind of oil in his head is some sort of compensating mechanism that
_________(15)adjusts the internal pressure of his body.But since you can"t bring a
live whale into the laboratory for study,no one knows just how these things work. _________(14)