如图，以△ABC的边BC为直径的⊙O分别交AB、AC于点D、E，连结OD、OE，若∠A＝65°，则∠DOE＝____°．

如图是科学家对水稻根进行单侧光照后的生长状况，下表是处理后的实验结果．请回答：

（1）根的背光性说明了生长索的作用具有____ 性的特点．

（2）实验时水稻根应垂直向下，是为了排除无关变量____ 对实验的影响，该实验的对照组为表中____处理方式．

（3）分析表中实验结果推测：生长索分布不均既可能与____ 有关，也可能与____ 有关．

阅读短文从方框中选择适当的单词填空（每词限用一次）

     Long long ago, there was a very old man called Yu Gong. There were two ____ Near his house. They were so high and big that it took a____ time to walk to the other side.The old man told his family that they should help him to move the mountains.
    Yu Gong and his family kept on digging day after day and year after year. ____ a god was so moved ____ Yu Gong that he sent two gods to take the mountains away.
    This story reminds us that you can never know what will happen ____ you don't try to do it．