When I was a little girl, I lived with my grandparents in a small village(村庄).The life there was 1, and I liked it very much. I had many friends and I liked playing with them 2 . After rainy days, there was much 3 in the river(河) near our house. I often went there to get4with my friends. I had 5fun living there.
Now I live in a big city. I study in a school, but I6my life here. It’s too busy and it often makes me very7. Now the most interesting thing for me is to go to my grandparents’ home to8my vacation. Every time I can’t  9to go there. I  10  a quiet life. I hope to live in a village when I’m older. 

在下列各式子$\frac{1}{2}ab,\frac{n}{m},s=\mathrm{\pi }{\mathrm{R}}^2,\frac{1}{\mathrm{b}}\left(\mathrm{x}-\mathrm{y}\right),3,{\mathrm{a}}^2+2\mathrm{a}\mathrm{b}+{\mathrm{b}}^2$中，代数式有（　　）

在光滑的水平面上有一个物体靠墙静止着，如图所示．

4.2x－0.6=1.5       x=____