Exercise 1. В каждой паре предложений поставьте глагол в одной из форм: Past Perfect или Past Perfect Continuous.
1.to listen
My head hurt because I ... to music for three hours. – I knew the names of the robbers because I ... to the news on TV. 
2.to build
They ... a new school for six months when there was an earthquake. – They ... a new block of flats by December. 
3.to fly
By the time the sun went down the couple ... over the Pacific ocean for five hours. – By the time the sun went down the couple ... more than 500 km over the Pacific ocean.

My head hurt because I had been listening to music for three hours. – I knew the names of the robbers because I had listened to the news on TV.  They had been building a new school for six months when there was an earthquake. – They had built a new block of flats by December.  By the time the sun went down the couple had been flying over the Pacific ocean for five hours. – By the time the sun went down the couple had flown more than 500 km over the Pacific ocean.