@Nhy
23 . If we lived without air , we would die
24 . If she hadn't had a visa , she couldn't have come to that country
25 . If there weren't the sun , man would live in the darkness
26 . It he hadn't had money , he wouldn't have bought such a big house
27 . If he didn't smoke , he wouldn't be so weak
28 . If it hadn't been cold yesterday , we could have gone swimming
29 . If it weren't very cold , we could go swimming
30 . If I hadn't been busy , I would have watched TV last night