下图表示在某晴天的上午，将一盆植物的部分枝叶用干燥的透明塑料袋罩住，扎紧袋口并置于阳光下。一段时间后，塑料袋内壁上会出现小水珠，这是植物____作用的结果。

书面表达

       某英文报举办“家乡的变化”主题征文活动。请你根据以下提示，以“The Changes in My Hometown”为题，用英语写一篇80词左右的短文。

  过去：

  1生活贫困，房屋破旧。

  2污染严重，垃圾遍地。

  3交通不便，游客很少。

  现在：

  1生活：住房宽敞明亮，许多人有了自己的汽车。

  2环境：山更绿了，水更清了，天更蓝了。

  3旅游：每年有成千上万来自世界各地的游客。

  将来：请你展望家乡的未来。

  注意：1. 文中不得出现具体的地名。    2. 标题和开头已给出，不计入总词数。

                                                  The Changes in My Hometown

        In the past, my hometown was very small.                                                                                                                                          

    Many teenagers have  ____. But sometimes these can get in the way of ____ schoolwork. Liu Yu is a ____ star on his school team. His dream is to be a  ____ runner when he ____ up. His parents won't allow him ____ so much although they have nothing ____ running. They think their son needs to think about other possible____. Liu Yu ____ with them. He thinks his parents are too strict with him. He also thinks it's very important ____ for himself. Only in this way can he have a chance to achieve his dream.

某班第一小组6名女生在测仰卧起坐时，记录下她们的成绩（单位：个/分）：45，48，46，50，50，49．这组数据的平均数是（　　）