tolong dijawab ya mohon bantuannya besok mau dikumpul

1.what have you learned since you came here?
how many friends have you made? I hope you have already met a lot of interesting people.

2.since classes began, I haven't have much free time. i had several big tests to study for.

3.medical scientist have made many important discoveries.

4. I went, I visited.

5. I haven't seen them for ages and they have never been at my place before.