如图是某机器零件的设计图纸，用不等式表示零件长度的合格尺寸，则长度L的取值范围是（　　）

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牵牛花清晨开放，傍晚关闭，这种现象说明生物具有哪种特征（  ）

读短文，掌握其大意，然后从A、B、C、D四个选项中选出一个可以填入相应空白处的最佳答案。

    Have you ever planted a few trees on Tree Planting Day? Each year, millions of people, both  1 , plant a lot of trees. But this may not be the best way to make your home a  2 place.

   Last week we visited a park in Hebei. We were  3  to find most of the trees had been burned. The workers told us that the trees   4   soon after they were planted because they weren’t watered well enough.   5workers burned them and cleaned the place for   6  trees to be planted this year.   7  a card found in one of the dead trees, a student wrote, ＂I hope this tree will grow up with me to   8   the backbone(栋梁) of our country.＂The workers said that the survival(存活) of the trees was really more important than  9   trees were planted.

    Some people in Beijing now have a new idea that they can donate(捐赠) some money and let professionals (专业人士) plant and  10  the trees.