The Greatest Mystery Of Whales
The whale is a warm-blooded，air-breathing animal，giving birth to its young alive，sucking them--and，like all mammals，originated on land.There are many front flippers，used for steering and stability, are traces of feet.
__________ . of this.Its Immense strength is __________ . into the great body of the big whales，and in fact most of a whales body is one gigantic muscle.The blue whales pulling strength has been estimated __________ . 400 horsepower.One specimen was reported to have toweda whaling vessel for seven hours at the __________. of eight knot .
An angry whale will __________ . A famous example of this was the fate of Whaler Essex, __________ . was sunk off the coast of South America early in the last century.More recently, steel ships have __________ . their plates buckledin the same way.Sperm whaleswere known to seize the old-time whaleboats in their jaws and crush Them.
The greatest __________ . of whales is their diving ability.The sperm whale dives to the Bottom for his __________ . food，the octopus.In that search he is known to go as far Down as 3,200 feet, where the. __________ . is 1,400 pounds，to a square inch.Doing so he
Will __________ . underwater long as one hour.Two special skills are involved in this storing up enough __________. and tolerating the great change in pressure.Just how he does it scientists have not __________ . .It is believed that some of the oxygen is stored in a special __________ . 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 __________ . adjusts the internal pressure of his body.But since you cant bring a live whale into the laboratory for study, no one knows just how these things work.
51 A aspects
B signs
C ways
D reasons
52 A worked
B divided
C built
D moved
53 A at
B in
C of
D with
54A number
B degree
C distance
D rate
55A abandon
B attack
C leave
D board
56A as
B who
C which
D that
57A had
B operated
C Seen
D caught
58A interest
B job
C danger
D mystery
59A favorite
B fast
C new
D sufficient
60A depth
B pressure
C level
D size
61A set
B become
C remain
D rest
62A heat
B energy
C food
D oxygen
63A witnessed
B determined
C applied
D calculated
64A system
B place
C arrangement
D equipment
65A mentally
B artificially
C manually
D automatically