Ответ:

1. Tod and Henry have been swimming in the lake since 11 a.m. (время- Present Perfect Continuous)

2. Tod and Henry haven’t been swimming in the lake since 11 a.m.

3. Tod and Henry have been swimming in the lake since 11 a.m, haven’t they?

4. Have Tod and Henry been swimming in the lake since 11 a.m.?

5. Have Tod and Henry been swimming in the lake or in the pool since 11 a.m?

6.

1) Where have Tod and Henry been swimming since 11 a.m?

2) When have Tod and Henry been swimming in the lake?

3) What have Tod and Henry been doing in the lake since 11 a.m.?

4) Who has been swimming in the lake since 11 a.m.?