阅读材料，回答问题

材料：青春，多少诗人讴歌、吟唱的美妙字眼！当你逐渐步入这个绚丽多姿又变幻不定的人生重要时期，从生理到心理，从思想到行为，你都会发生巨大的变化。这一时期，幼稚与成熟，独立与依赖，相互交织。让我们坦然面对变化，悦纳自己，克服烦恼，健康身心，弹奏出一曲积极进取、美妙和谐的青春乐章。某校七年级（2）班围绕“解读青春”这一主题展开社会实践活动，请你参与进来。

    I'm Lisa. My father is a doctor. He often drives his car to work. My mother is an English teacher. She always walks to work. She says walking is a good way to exercise. My mother also likes going shopping. She often does some shopping on Sundays. I am a student. I usually ride a bike to school, but sometimes I come to school by bus. I like watching TV. I only watch TV on Saturday and Sunday evenings.

读课文《小草和大树》，理层次。

阅读《小树和大树》，划分一下层次：