某同学学习过机械效率后，提出了一问题：“斜面的机械效率与斜面的倾斜程度有没有关系？”针对这个问题他做了在同一斜面上匀速拉动物块A的探究实验，如图所示，并记录实验数据如下：
（1）通过对上述实验数据的分析，你认为斜面省力情况与斜面倾斜程度的关系是：斜面越陡，越 （选填“省力”或“费力”）；
（2）通过对上述实验数据的分析，你对斜面机械效率的问题可获得的初步结论是 ；
（3）如果该同学还想要探究斜面的机械效率与物重的关系，实验时应控制哪些条件不变： 。
（1）费力
（2）对同一斜面，在物重和物体沿斜面移动距离相同条件下，斜面越陡，机械效率越高。
（3）斜面的倾斜程度、斜面与物体接触面的粗糙程度、物体沿斜面移动的距离。
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| Li Dong is a farmer. He has a very big 1 . On the farm, he grows oranges, grapes and bananas. Many people come to 2 his farm. He is a successful young man and becomes very famous. In 2003, he went back to his hometown 3 he finished middle school. "What work can I do?" he said to himself. Then he had an idea. "I'm interested 4 farming. I can grow fruit!" He began to watch many 5 on TV about growing fruit. He also read a lot of books about it. Then he went to 6 on Mr Wang's farm for two years. He learned a lot there. In 2005, he started his own fruit farm. 7 , Li Dong's farm was small. But now, his farm is much 8 . His fruits are very good. He sends them to many big 9 in China, such as Shanghai, Beijing and Guangzhou. He also grows vegetables and raises chickens on his farm. His family eats very 10 food. He has a very happy family. | ||||
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