提供一个英语语法练习，需要填写适当的词形和语法。
英语语法练习题，包括填空和改错题。
填空题：

1. She always __________ (complain) about her job, but never does anything to improve it.

2. The children __________ (play) outside when it started to rain.

3. I __________ (not see) that movie yet, but I heard it's really good.

4. My grandmother __________ (cook) delicious meals when she was younger.

5. The students __________ (study) hard for their final exams.

6. You __________ (not be) here tomorrow, so don't forget to finish your work today.

7. I __________ (not be) able to attend the meeting because I have a doctor's appointment.

8. She __________ (paint) the walls of her room yesterday.

改错题：

1. My brother is study at the university. __________

2. She is more smarter than her sister. __________

3. He don't like to eat vegetables. __________

4. They enjoys spending time together. __________

5. Yesterday, she go to the store to buy some bread. __________

答案：

填空题：

1. complains

2. were playing

3. haven't seen

4. used to cook

5. are studying

6. won't be

7. won't be

8. painted

改错题：

1. My brother is studying at the university. (is study --> is studying)

2. She is smarter than her sister. (more smarter --> smarter)

3. He doesn't like to eat vegetables. (don't --> doesn't)

4. They enjoy spending time together. (enjoys --> enjoy)

5. Yesterday, she went to the store to buy some bread. (go --> went)