Question

阅读理解 　　Which animal has the fastest snapping jaw(突然合住的颚)? If you're guessing a shark or perhaps a larger animal, you'll have to think smaller．The trap-jaw ant, which lives in Central and South America, moves its mouth parts at 35 to 63 meters per second．Another way to think about this is that the ant's jaws close at 125 to 233 kilometers per hour．That's 2,300 times faster than the blink of an eye． 　　Scientists were able to measure the amazing jaw speed using high-speed video techniques．Sheila Patek, a biologist, says the key is that the jaws have a springy(有弹性的)system, which is critical in getting explosive(爆发性的)speeds． 　　Consider a bow and arrow．If you try to throw an arrow with your arm, it won't go very far．If you use a bow, elastic energy stored in the bow is freed almost immediately when you let go of the arrow with your finger．That's exactly what really fast organisms are doing． 　　Maybe even more amazing than how fast these ants grab food or even enemies is how they use this same energy to move．As the ant closes its jaws, it uses them to push off the ground－all faster than the eye can see without slow motion video．A snap of the jaw can send an ant up to 8.3 centimeters into the air．That's like someone who is 1.7 meters jumping 13 meters high! Not only can they quickly escape from enemies, but often a group of ants will start jumping all at once．It would be hard for their enemies to grab just one． (1) The fast speed of the trap-jaw ants' jaws lies in ________． [　　] A． their light bodies B． their springy systems C． their living environment D． the length of their jaws (2) What does the passage use “a bow and arrow” as an example to show? [　　] A． How an arrow gets so much energy to fly． B． Why the trap-jaw ants have a springy system． C． Why the trap-jaw ants' jaws move so fast． D． How a bow and arrow works． (3) Which of the following things may amaze the scientists most? [　　] A． How high the ants can leap by using their jaws． B． How quickly the trap-jaw ants can move on the ground． C． How wonderfully the springy system in the trap-jaw ants' jaws works． D． How quickly the trap-jaw ants can grab food or enemies． (4) According to the passage, the trap-jaw ants' jaws keep them safe because ________． [　　] A． they can catch their enemies easily with their jaws B． their jaws make them difficult to recognize C． their jaws help them to find food easily D． their jaws help them to escape from their enemies

Answer 1

答案：1．B;2．C;3．A;4．D;