Ms.Sue is this right?

1)The puppy came (to our tent) and slept (at the foot) (of my sleeping bag).

2)A skywriter flew (over the field) (during the game).

3)The city was (without power) (for several hours)

4)The cross-country team ran down the avenue and through the park.

You have correctly identified the prepositional phrases in the first three sentences, yes.

How about the fourth sentence?

And which words are the subjects?

down the avenue

through the park

Hello! I'd be happy to help you determine if the sentences are correct.

1) The puppy came (to our tent) and slept (at the foot) (of my sleeping bag).
This sentence is correct. It uses prepositional phrases "(to our tent)" and "(at the foot)" to provide additional information about where the puppy came and slept.

2) A skywriter flew (over the field) (during the game).
This sentence is also correct. It uses prepositional phrases "(over the field)" and "(during the game)" to provide additional information about the skywriter's location and time.

3) The city was (without power) (for several hours).
This sentence is correct. It uses prepositional phrases "(without power)" and "(for several hours)" to provide additional information about the duration and the city's situation.

4) The cross-country team ran down the avenue and through the park.
This sentence is correct. It uses prepositional phrases "down the avenue" and "through the park" to provide additional information about the route taken by the cross-country team.

Overall, all the provided sentences are grammatically correct and use prepositional phrases effectively to provide additional information. Great job!