Student: Why [?] (he/decide) to sail west? 

Teacher: He decided to sail west after listening to the description of a mysterious land. One day, when he was a boy, he saw an old tattered ship rowing very slowly. He recognized the ship and went to talk to Bjarni Herjolfsson, the owner, who had been away for a year. 

Student: Why was Leif in the harbour? What [?] (he/do) when he saw Bjarni's ship? 

Teacher: He was watching the ships come into the harbour. As a boy he liked being in the harbour. He and his friends liked watching the ships and listening to the tales of the sailors. 

Student: What [?] (Bjarni/say) to Leif Eriksson? 

Teacher: He said, "My men and I [?] (sail) back to Greenland but we got lost because it was foggy for many days."

Student: What [?] (they/see) when the fog lifted? 

Teacher: They saw a beautiful land with trees but they [?] (not/go) ashore because they wanted to arrive back in Greenland. Bjarni described this land so beautifully that when Leif grew up, he decided to explore it.