1. We just (begin) our lesson. 2. He already (introduce) us. 3. I (leave) my copybook at home yesterday. 4. She (get) a bad mark last week. 5. Mike (read) this exercise before the lesson. 6. Sam and I (meet) a week ago.

Past Simple / Present Perfect:

1. We just have begun our lesson.
2. He already has introduced us.
3. I left my copybook at home yesterday.
4. She got a bad mark last week.
5. Mike read this exercise before the lesson.
6. Sam and I met a week ago.