共用题干 The Greatest Mystery of WhalesThe whale is a warm一blooded,air-breathing animal,giving birth to its young alive,sucking them一and, like all mammals,originated on land. There are many________________(51)of this. Its front flippers(鳍状肢), used for steering and stability,are traces of feet.Immense strength is________________(52)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________________(53) 400 horsepower. One specimen was reported to have towed(拖)a whaling vessel for seven hours at the _______________ (54)of eight knot(节).An angry whale will________________(55).A famous example of this was the fate 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. Sperm whales(抹香鲸)were known to seize the old-time whaleboats in their jaws and crush them.The greatest________________(58)of whales is their diving ability.The sperm whale dives to the bottom foi his________________(59)food,the octopus(章鱼).In that search he is known to go as far down as 3 , 200 feet, where the________________(60)is 1,400 pounds,to a square inch.Doing so he will________________(61)underwa-ter as long as one hour. Two special skills are involved in this storing up enough________________(62)(allwhales are air-breathed)and tolerating the great change in pressure.Just how he does it scientists have nol_______________ (63).It is believed that some of the oxygen is stored in a special________________(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 of a compensating mechanism that________________(65)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. _________(51)
A.aspects B.signs C.ways D.reasons正确答案B
