An example of a species of frog that， at far as is known， has become extinct， is the platypus frog. Like the well-known Australian mammal it was named after， it exhibited some very strange behaviour； instead of giving birth to tadpoles in the water， it raised its young within its stomach. The baby frogs were actually born from out of their mother‘s mouth. Discovered in 1981， less than ten years later the frog had completely vanished from the crystal clear waters of Booloumba Creek near Queensland‘s Sunshine Coast. Unfortunately， this freak of nature is not the only frog species to have been lost in Australia. Since the 1970s， no less than eight others have suffered the same fate.
One theory that seems to fit the facts concerns the depletion of the ozone layer， a well documented phenomenon which has led to a sharp increase in ultraviolet radiation levels.The ozone layer is meant to shield the Earth from UV rays， but increased radiation may be having a greater effect upon frog populations than previously believed. Another theory is that worldwide temperature increases are upsetting the breeding cycles of frogs.
TRUE／FALSE／NOT GIVEN 1.Frogs are disappearing only from city areas. 2.Frogs and toads are usually poisonous. 3.Biologists are unable to explain why frogs are dying. 4.The frogs‘ natural habitat is becoming more and more developed. 5.Attempts are being made to halt the development of wet marshland. 6.Frogs are important in the ecosystem because they control pests. 7.The platypus frog became extinct by 1991. 8.Frogs usually give birth to their young in an underwater nest. 9.Eight frog species have become extinct so far in Australia. 10.There is convincing evidence that the ozone layer is being depleted. 11.It is a fact that frogs‘ breeding cycles are upset by worldwide in creases in temperature.如果觉得《模拟题：雅思阅读经典模拟题（一）》历年真题,yashi不错，可以推荐给好友哦。