1. I can talk about different ways to keep fit.
play ping-pong

play basketball; run; swim; eat vegetables

题目要求列举不同的保持健康的方式，play ping-pong是运动类，结合七年级下册所学，可从运动、饮食、作息等方面思考。运动类还有play basketball, run, swim；饮食类如eat vegetables；作息类如get enough sleep。

2. I can tell others about how often I do sport or exercise.
always

usually; often; sometimes; never

题目要求填写描述做运动或锻炼频率的词，七年级下册所学频率副词有always, usually, often, sometimes, hardly ever, never。根据题目已给出always，需补充其他常见频率副词。

3. I can talk about things that I own and identify ownership.

This is my book. That is her pen. These are our desks. Those are their bags.

题目要求谈论自己拥有的东西并识别所有权，七年级下册相关内容涉及形容词性物主代词(my, your, his, her等)和名词性物主代词(mine, yours, his, hers等)的使用，以及句型"This is my.../That is her.../These are our.../Those are their..."等。

4. I can explain the importance of doing sport and exercise.

Doing sport and exercise is important for several reasons. Firstly, it helps to keep our bodies healthy and strong. Regular physical activity can improve our cardiovascular health, increase our muscle strength and flexibility, and reduce the risk of chronic diseases such as obesity, diabetes, and heart disease. Secondly, sport and exercise can also have a positive impact on our mental health. It can reduce stress, anxiety, and depression, and improve our mood and self-esteem. Finally, doing sport and exercise can be a fun and social activity. It allows us to meet new people, make friends, and enjoy the outdoors. In conclusion, doing sport and exercise is essential for our overall health and well-being.

本题要求解释进行体育运动和锻炼的重要性，可从身体健康、心理健康、社交等方面用简单英语表述。
1. It's good for our health.
2. It can make us strong.
3. It helps us relax.

How do we keep fit?

We should eat healthy food. We should do exercise regularly.

根据七年级下册英语关于健康生活的内容，保持健康的常见方式有合理饮食和规律锻炼。