I can't believe we _____ (sightsee) for the last two hours!
I can't believe we've been sightseeing for the last two hours!
Eric _____ (cycle) along the coast since twelve o'clock so he was extremely sore.
Eric had been cycling along the coast since twelve o'clock so he was extremely sore.
The cost of living _____ (get) more and more expensive nowadays.
The cost of living is getting more and more expensive nowadays.