任务二:根据短文内容,完成句型转换。
1. We have cleaned the community park for two hours every weekend. (对画线部分提问)
have you cleaned the community park every weekend?
2. Ms Li has volunteered in the community for five years. (对画线部分提问)
has Ms Li volunteered in the community?
3. The volunteer team has helped over 200 people in need so far. (改为否定句)
The volunteer team over 200 people in need so far.
4. Lily has sung old songs for the elderly in the community nursing home. (改为一般疑问句并作肯定回答)
— Lily old songs for the elderly in the community nursing home?
—Yes, she .
5. I have been a team member for one year. (用 since 改写,句意不变)
I have been a team member the summer vacation of 2025.

1. How long
2. How long
3. hasn't helped
4. Has; sung; has
5. since

1. 画线部分for two hours表示动作持续的时长，对时间段提问要用疑问词组How long，句首首字母大写。
2. 画线部分for five years是表示动作持续的时间长度，对该部分提问用疑问词组How long，适用于现在完成时中询问动作持续多久。
3. 本句为现在完成时，变为否定句时，直接在助动词has后加not，缩写为hasn't，后面保留动词的过去分词helped即可。
4. 现在完成时改为一般疑问句，需要将助动词has提至句首，谓语动词仍使用过去分词sung；现在完成时的肯定回答结构为Yes, 主语+has。
5. 现在完成时中，for后接时间段表示动作持续的时长，since后接过去的时间点表示“自从……以来”，此处替换结构保持句意不变，填入since。

任务三:根据短文总结语法规律,用 since 或 for 填空。
现在完成时与 since 或 for 搭配,用来表示从过去持续到现在的动作或状态,强调动作的“持续性”。

1. She has been a volunteer last August.
2. He has volunteered here a long time.
3. I have been a member of the Red Cross six years.
4. They have worked here 2023.
5. We have known each other we were children.

1. since
2. for
3. for
4. since
5. since

本题考查现在完成时中since和for的用法区分：
1. since意为“自……以来”，后面需要接过去的时间点（如具体月份、年份等）或者一般过去时的句子，用来引出动作开始的时间起点。
2. for意为“持续了……时间”，后面需要接表示一段时长的短语，用来表示动作持续的总长度。
逐题分析：
1. 空格后last August是过去的时间点，符合since的使用规则。
2. 空格后a long time是一段时长，符合for的使用规则。
3. 空格后six years是一段时长，符合for的使用规则。
4. 空格后2023是过去的时间点，符合since的使用规则。
5. 空格后we were children是一般过去时的句子，符合since的使用规则。