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.
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 size
11 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