One possible version

A voluntary activity

Last Sunday, our class launched a voluntary activity. Its theme is to make the city more beautiful and advocate a low-carbon lifestyle. In the morning, we went to plant trees in the suburbs. We worked in cooperation. Some dug holes, some carried and planted trees, and some watered them. In the afternoon, we went to People's Square to hand out leaflets, raising people's awareness of environmental protection. Most of the students think highly of the activity, which will surely produce a positive effect on their daily life.

As far as I'm concerned, it's everyone's duty to protect the environment. As long as there is the possibility of saving our planet, take action now before it is too late. Low carbon living is surely a way of great significance.(120词)

试题分析：本文是篇材料作文，材料具有鲜明的时代特色，学生很容易把握写作要求和写作目的。考生在写作之前必修认真审题，首先要注意文章的时态，上周日，你班开展以“美化城市环境，倡导低碳生活”为宗旨的志愿者活动。活动内容包括：上午去郊区植树；下午去广场宣传，分发传单。请你就这个活动为校报写一篇120个左右词的短文。所以要用一般过去时；人称应该用第一人称we注意字数的要求。同时还要注意不能根据材料逐字逐句的翻译应该注意句子的衔接，以提高作文的档次。

【亮点说明】文中使用了非常好的短语和句子为文章增色不少，比如think highly of ,as far as I'm concerned,as long as,take action，还运用了动词的不定式形式作表语，非谓语的-ing形式做状语，which引导的非限制性定语从句等等。