VA ROG!   complete the sentences by using the past simple or the past perfect continuous form of the verbs in brackets: 1.when leonardoda vinci built his helicopter he.......(work) on his design for many years. he ....(draw)birds  in flight to learn about aerodynamics. 2.we....(fly) for twenty minutes when the pilot .... (announce) we had to go back because of bad weather. 3.the teacher....(ask) for my project on inventions for weeks  when I finally ...(give) it to her last Monday. 4.I found out why my pen friend ... (not get) my letters.I...(send) them to the wrong address! 5.our favourite band...(play)for only ten minutes  when there ...(be) a power cut and the concert had to be  cancelled. we werw upset because we ...(die) to see them for years.