Ответ:

3.

1 Slave trade stopped over 200 years ago.

2 Who did you like most in your last school?

3 We didn't understand lecture in last week.

4 When did you take your last exam?

5 When did Jack arrive to tell us the news?

6 Why did you start learning English?

4.

1 The last major festival in my country was the Christmas.

2 I liked Ivan the most in my last school.

3 I took my last exam 2 weeks ago.

4 I started to learn english,because it was interesting.