把Q=4×10^﹣9C的试探电荷放在电场中的A点，具有的电势能6×10^﹣8J，求

物体由静止出发从光滑斜面顶端自由滑下，当所用时间是下滑到底端所用时间的一半时，物体的动能与势能（以斜面底端为零势能参考平面）之比为（   ）

（1）已知多项式﹣$\frac{2}{3}$x²y^m+1+xy²﹣2x³+8是六次四项式，单项式﹣$\frac{3}{5}$x^3ay^5﹣m的次数与多项式的次数相同，求m，a的值；

（2）已知多项式mx⁴+（m﹣2）x³+（2n+1）x²﹣3x+n不含x²和x³的项，试写出这个多项式，再求当x=﹣1时多项式的值．

Do your characteristics match __________ your star sign says about you?

注意：1）.每处错误及其修改均仅限一词；
2）.只允许修改10处,多者（从第11处起）不计分。
    More and more foreigners like to come to China. Last Friday our school was invited a foreign teacher in our city give a class to the students of Senior Grade Two. We found his class interested. I learned a lot from him. The teacher had a free talk to us with easy English . He spoke slow so that we could understand him well. Sometimes he repeated what we don't understand. My classmates were all active in the class. To his joy, I understood everything the teacher said. And I was able to ask question in English. This class encouraged me very much. I'm sure that until we keep on practising, it will be easy for us to learn speaking English well.