如图所示，一个静止小球从A点沿粗糙程度相同的轨道下滑，经B点到达C点，从A点到达C点的过程中，小球的动能____，小球的重力势能____，小球的机械能____．（选填序号）

①保持不变；②一直减小；③先增大后减小；④一直增大；⑤先减小后增大．

化简：（﹣$\frac{y}{x^2}$）³÷（$\frac{y^2}{x^3}$•$\frac{x^2}{y}$）=____ 

短文填空

    One ____(rain) night I was driving along a lonely highway ____I saw a man walking rapidly ahead of me along the side of the road.It was pouring rain and I slowed down to avoid splashing him as I went by.

    He misunderstood and thought I was offering a ride，and ran towards my car. He was very tall and had a full beard, ____ scared me. I stepped on the gas pedal  ____（leave）quickly and I saw the look of total despair in his eyes. Suddenly，all fear was  ____(go) and I backed up and unlocked my car door，praying this was not the ____(big) mistake in my life but somehow knowing it would be okay.

    The man's truck had got stuck ____the mud. He ____(walk) for miles.No one would pick  ____up and his wife was giving birth to their first child in the hospital. He had cried at the thought that he might not be there. ____ fortunate), we arrived in the hospital before his son was born.