如图，已知∠1=∠2=∠3=55°，则∠4的度数是（　　）

用绳子拉小车在光滑的水平面上加速运动，当绳子突然断裂后小车的运动速度将（   ）

    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 were3 to find most of the trees had been burned. The workers told us that the trees 4soon after they were planted because they weren't watered well enough. 5 workers 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 professional (专业人士) plant and 10 the trees.

用反证法证明命题“三角形中必有一个内角小于或等于60°”时，首先应该假设这个三角形中（　　）

根据检索表，“能进行光合作用，自养;能开花结果，用种子繁殖;叶脉平行，须根系”的植物属于（  ）