题目内容：
The Greatest Mystery Of Whales The whale is a warm-blooded, air-breathinganimal, giving birth to its young alive,sucking them--and, like all mammals,originated on lanD．There are many ____________(51) Of this. Its front flippers(鳍状肢), usedfor steering and stability, are traces of feet.Immense strength is____________ (52) intothe great body of the big whales, and in fact most of a whale's body is onegigantic muscle. The blue whale's pulling strength has been estimated ____________(53) 400 horsepower. One specimen was reported to have towed (拖) a whaling vessel forseven hours at the____________ (54) of eight-knots (节).
Anangry whale will ____________ (55) a ship. A famous example of this was thefate of whaler Essex, ____________ (56) was sunk off the coast of South America early in the last century. More recently,steel ships have ____________ (57) their plates buckled (使弯曲) in the same way. Spermwhales (抹香鲸) were known to seize the old-timewhaleboats in their jaws and crush them.
The greatest____________ (58) of whales istheir diving ability. The sperm whale dives to the bottom for his ____________(59) food, the octopus (章鱼).In that search he is known to go as far down as 3,200 feet, wherethe ____________ (60) is 1,400 pounds, to a square inch. Doing so he will____________(61) underwater long as one hour. Two special skills are involved in this:storing up enough ____________ (62) (all whales are air-breathed) and toleratingthe great change in pressure. Just how he does it scientists have not____________ (63). It is believed that some of the oxygen is stored in aspecial____________ (64) 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 ofcompensating mechanism that ____________ (65) adjusts the internal pressure ofhis body. But since you can't bring a live whale into the laboratory for study,no one knows just how these things work. A．aspects
B．signs
C．ways
D．reasons
参考答案：
答案解析：