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(鳍状肢)，used for steering and stability, are traces of feet.______(1)of this.Its 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 knot (节). An angry whale will ______ (5) 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.
1 A aspects B signs C ways D reasons
2 A worked B divided C built D moved
3 A at B in C of D with
4 A number B degree C distance D rate
5 A abandon B attack C leave D board
6 A as B who C which D that
7 A had B operated C Seen D caught
8 A interest B job C danger D mystery
9 A favorite B fast C new D sufficient
10 A depth B pressure C level D size11 A set B become C remain D rest
12 A heat B energy C food D oxygen
13 A witnessed B determined C applied D calculated
14 A system B place C arrangement D equipment
15 A mentally B artificially C manually D automatically