分集介绍:直角坐标是常用的坐标法,但是对于一些特别的问题,在直角坐标系下处理就显得有点笨拙了。这个时候,我们不妨试试极坐标。它可以使得问题变得出乎意料地简洁, 也能让问题

发表于:2018-12-09 / 阅读(241) / 评论(0) 分类 麻省理工学院公开课:单变量微积分

A carousel has big, plastic horses. Each horse is a different color. She likes the white horse. She gets on the white horse. It has a black tail. She sits in the saddle. She holds onto the pole. The music starts. The carousel starts. It goes round an

发表于:2018-12-31 / 阅读(54) / 评论(0) 分类 儿童英语小故事

1. 【真题】The shy girl felt ___ and uncomfortable when she could not answer her teacher’s questions.(1998.6) A. amazed B. awkward C. curious D. amused 2.【真题】We welcome rain ,but a(an) _

发表于:2019-02-25 / 阅读(65) / 评论(0) 分类 英文语法词汇