1. Has the teacher come yet? — Yes, he has. — When did he come? — He came half an hour ago.
2. Where is Popov the student? — I have just seen him. — When did you see him? — I saw him half an hour ago.
3. I've done the exercises today, though my sister did them yesterday.
4. Have you been to Netherlands yet? — No, I've never been there.
5. What English port have you been to? — I was in London. — When were you there? — I was there in 1988.