1.Have you ever been to London?Yes,I have been there several times.-When you were there last time?
2.Have you seen Mery this week?But I saw her last month.
3.When have you entered the Nautical College?-I entered it last autumn.
4.The ice-breaker Sibir has just arrived at the pilot station.
5.We have learned ...But I knew about..
6.When you made yours first voyage?-I made it four months ago,but my brother has just put to sea.
7.The sailors have already launched the life-boat.When did the lift life-boat?They lifted it 10 minutes ago.