如图，点F是梯形ABCD的下底BC上一点，若将△DFC沿DF进行折叠，点C恰好能与AD上的点E重合，那么四边形CDEF（　　）

今年（2015年），我国将举行抗日战争胜利70周年庆典。八年抗日战争，中国人民最终取得了伟大胜利，其重大意义是(   )

①是一次取得完全胜利的民族解放战争          

②标志着中国新民主主义革命已经取得胜利          

③洗雪了近代以来的民族耻辱，成为中华民族由衰败到重新振兴的转折点         

④中国人民从此站立起来，成为新国家新社会的主人  

若$\sqrt{x+1}+\sqrt{y-3}$＝0，则(x－1)²＋(y＋3)²＝____．

     April Fool's Day is supposed to be a day to play jokes on others in hopes of getting a good laugh and making one feel like a fool. However, the April Fool's Day of 2013 was quite different for my morn and me.

     That day my friend Jimmy and I were playing a game. I had dropped down from a bar(横木) many times in the past without ever having a problem, but that day the simple act of dropping to the ground became a nightmare(噩梦). I broke my arm.

Jimmy's dad heard my crying and rushed out to see what was going on. When he saw the

problem, he quickly put me into his truck and went inside to telephone my mom and let her know he would take me to the hospital. As that day was April Fool's Day, Mom was not buying it and really thought all this was a big joke. Mom was finally convinced(说服) by Jimmy's room. When she saw me, she broke down in tears because she felt so bad--she originally (起初) thought this was just a big prank(恶作剧).

      I guess one could compare this to the story of "The Boy Who Cried Wolf". Since I had pulled pranks before, it is no wonder that my morn didn't believe it. I as well as my morn was made to look like a fool that day. We both learned a valuable lesson.