根据句意，用括号内所给词的适当形式填空。
小题1:After so many ________ (year) practice, Li Na is a well-known tennis player.
小题2:We’ll have a surprise party for my mother’s ________ (forty) birthday next Saturday.
小题3:The higher the mountain is, the ________ (thin) the air is.
小题4:To tell the ________ (true), I don’t like the drinks in that café.
小题5:It’s a (an) ________ (usual) experience, few people have chances to do it.
