A: Were you by the river at four o'clock?
B:Yes.We were sitting under some trees,near the bridge.A lot of people were swimming in the river.
A:Was Adam with you?
B:Adam?No,he was at home.He was working on his History project.
A:What about Tim and Sarah?
Were they at home,too?
B:Yes.They were revising for their exams.
C)were you walking
E) was playing