Question

On leaving the hall, the students (to thank) tie professor who (to deliver) the lecture. We already (to cover) about ten miles when Peter, who (to look) out of the window for the last five or ten minutes, suddenly exclaimed, "Here is the station!"

Answer 1

Thanked.who had delivered..have already covered...who had been looking 

Answer 2

On leaving the hall, the students thanked the professor who had delivered the lecture. They had already covered about ten miles when Peter, who had been looking out of the window for the last five or ten minutes, suddenly exclaimed, "Here is the station!"

After the lecture, the students expressed their gratitude to the professor as they left the hall. They had been traveling for quite a while, covering a distance of approximately ten miles when Peter, who had been observing the surroundings outside the window for the past few minutes, suddenly noticed the station and exclaimed in excitement.