在本单元的学习中，主要涉及的是英语语法中的动词过去式和词汇运用，这在七年级英语学习中是非常基础且重要的部分。动词过去式是英语语法的基础元素，用于描述过去发生的事情。以下是对题目中给出的动词过去式的答案：
1. did - did
2. play - played
3. clean - cleaned
4. visit - visited
5. study - studied
6. practice - practiced
7. have - had
8. stay - stayed
9. read - read
10. watch - watched
11. cook - cooked
12. die - died
13. get - got
14. sit - sat
15. look - looked
16. go - went
17. run - ran
18. arrive - arrived
19. make - made
20. write - wrote
21. find - found
词汇运用部分主要考察学生对词汇的理解和应用能力：
A部分：
1. milk（喝牛奶对健康有益）
2. worry（不要担心你的儿子）
3. hear（请大声说，我听不到你）
4. grow（我们在农场上种了很多水果）
5. flowers（花园里有很多树和花）
B部分：
1. Luckily（幸运的是）
2. farming（他们告诉我们很多关于农业的事）
3. excited（听到这个消息我们很兴奋）
4. fed（吉姆喂了宠物狗并洗了他的碗）
5. lovely（琳达穿白色看起来很可爱）
练习题中还包含了对话和句型转换的练习，这些都是检验学生实际应用英语能力的关键环节。例如：
1. A: What did you have for breakfast yesterday?
B: No, I didn't. I got up late. I ate a lot for lunch.
2. A: I went to a movie over the weekend. What about you?
B: I didn't do my homework. I visited my grandma.
3. Where were you a moment ago?
4. Last Sunday, Anita studied for the math test. She always works hard.
5. Joy went shopping with his mother on Saturday afternoon.
6. Mr. Hall did some reading in the evening.
7. What about watching TV? There's a talk show.
8. Last week, she wrote a new song.
9. Most young people enjoy singing.
10. It was interesting to climb the mountain.
11. The people there are unfriendly. I don’t like them.
12. They had great fun playing in the water.
13. We are interested in the interesting movie.
14. Be quiet! Kate is studying for her math test.
15. I’d like a basket of tomatoes, please.
这些练习涵盖了动词一般过去时态、否定回答、疑问句、动名词和不定式等语法点，以及词汇在不同语境中的应用，对于七年级学生来说，熟练掌握这些内容对于提升英语综合能力至关重要。通过这样的练习，学生们可以巩固已学知识，同时培养良好的英语思维习惯和语言运用能力。
