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如图所示是小明“探究影响滑动摩擦力大小的因素”的实验,铜块和木块的大小和形状完全相同.在实验前,小明提出了以下几种猜想:

猜想一:滑动摩擦力的大小与压力的大小有关;

猜想二:滑动摩擦力的大小与物体间接触面的粗糙程度有关;

猜想三:滑动摩擦力的大小与物体间接触面积的大小有关;

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    Just several days ago, a violent storm hit our community. I looked out of the window and witnessed a tree being1 by the fierce winds. The branches bent, and swayed back and forth, thanks to their 2 to avoid breaking. The leaves desperately stuck to the branches because their life3 the tree. The powerful trunk that 4 the tree upright bent slightly backwards from the force in a battle to 5 its position.

    After the storm had passed, the tree gracefully returned to its 6 position standing tall among the chaos. It managed to7 the storm. It didn't look the same as leaves had shed from its branches and the soil had loosened a bit, but what 8 is that the tree won the fight for its life.

    For a long time I couldn't understand why this tree9 my attention the way it did. As time passed, it became10 that it wasn't just about the tree but about the roots, which, although unseen, dig deep into the soil providing11 and nutrition. The roots allow the tree to be able to take a 12 because they are there to support them.

    I couldn't but ask myself how deep the roots are in my life.13 the next time you catch your kids 14 when the job is driving you crazy, when you are underpaid and the15 is tight, and when the storms of life are raging, go back to your roots. Life is full of16.They will make you sway, make you17make you lose some leaves but the deeper your roots the stronger you stand.

    Faced with18 you might bend but don't break. No matter how hard the wind blows don't let life 19 you into an uncomfortable position. Your 20 lies in your roots.