根据短文内容及首字母提示，填写所缺单词，使短文意思完整。每空一词。
     The environment is becoming worse and worse . There are many kinds of pollution that I worry a____ . The most serious two are n____ pollution and air pollution , because people can't live h____ with polluted air. Animals can't live in the world , e____ . More and more people are becoming i____ because of  polluted air .
     I think factories should not p____  dirty water into rivers directly. We'd better go on foot or by bike i____ of by car . Finally , everyone must pay a____ to rubbish pollution . If everyone makes so much rubbish , one day we may live in a world f____  of rubbish . How terrible it will be ! We should take a____ to make our world cleaner and more beautiful

等腰梯形ABCD，上底边CD=1，腰AD=CB=$\sqrt{2}$，下底AB=3，按平行于上、下底边取x轴，则直观图A′B′C′D′的面积为____