1had
2lost
3would find
4would be
5would swim
6would watch
7would enter
8were
9wouldn't worry
10was
1I have already known him for five years.
2I have known him since 2000
3He has been surfing on the Internet for two hours.
4How long have you been watching this film?
5We haven't seen for ages.
6I have eaten nothing since morning.
7I have been doing my homework for the whole day.
8I have always loved pizza.
9I haven't eaten ice-cream for a month.
10We have been listening to music for an hour.