题目

We can always hear voices comparing the education systems in China and the US. It's true that61 exist a lot of differences, but this cannot be an excuse62 having a passive attitude toward studying in China. When I came back from the US last year and continued my senior middle school education in China, I sensed many great differences.  I thought that school in China was too hard for 63 (we) students, and that we didn't get to do enough fun exercise except running around playgrounds together. My mom had a long talk with me. After that, I realized that though high school l5．柏树和松树一共有750棵．柏树的棵数是松树的1.5倍．两种树各有多少棵？（用方程解答）