Complete the gaps with the correct prepositions (at, with, in, by)

1. Let's meet  
   [ ]  the afternoon, not
   [ ]  night.
2. We are experiencing some troubles
   [ ] this task.
3. The song was written
   [ ]  Madonna.
4. There is a spider
   [ ]  the corner of my room.
5. Mike prefers to drink coffee
   [ ] milk.
6. Sally met a lot of friends
   [ ] the party.