下列句子中划线的成语或俗语使用正确的一项是

根据短文内容，选择正确答案。
Hello, friends!
    My name is Zhou Dan. I'm a Chinese girl. I'm twelve. I'm from Zhengzhou, China. Do you know Zhengzhou? It's in the middle of China. I'm in No. 8 Middle School. There are about 900 students and 50 teachers in our school. It is a good school in Zhengzhou: I'm in Class 2 Grade 7. There are 49 students in our class: 29 girls and 20 boys. My English teacher is Miss Zhao Dan. Our names are almost the same, right? She is nice to me. We're good friends. I like English, and I like music, too. I want to find a pen-friend. Please write to me.
                                                              Yours,
                                                            Zhou Dan

如图中的五个半圆，两只小虫同时出发，以相同的速度从A点到B点，甲虫沿 $AD{A}_1$ ， $A_{1}E{A}_2$ ， $A_{2}F{A}_3$ ， $A_{3}GB$ 路线爬行，乙虫沿ACB路线爬行，则下列结论正确的是（    ）

类比法是化学研究物质的重要方法之一．草酸（H₂C₂O₄）的化学性质与碳酸相似．已知碳酸易分解，草酸在受热条件下也分解，仅生成三种氧化物．某校研究性学习小组对此展开探究：

世界上最大的大洲是（  ）