下列过程中，水分子发生了变化的是  （  ）           

    My family is ____(计划) a journey to China in the winter. Our first ____(选择) is to visit Beijing, one of the____(大) places in the world.. So we need to ____(预订) the plane tickets. To tell you the truth, we like going by train____ (好) . But we think it is too slow and it ____(花费) much time. Though going by plane is more____(昂贵的)，it goes____(快) and saves time. Some people may think it's not ____(安全) , but our family all____(赞同)it's our favorite way to travel.

如图，在⊙O中，AB，AC为互相垂直且相等的两条弦，OD⊥AB于D，OE⊥AC于E，求证：四边形ADOE是正方形．

读《春联》，根据课文内容填空

春联读起来____，____，如果下功夫背诵一些____，就能帮助我们感觉到其中的____，领略祖国语言的____。