10.a.1. i visited; 2. my friends are visiting; 3.visit;4.had been visiting;5.will visit;6.have just visited.b.1.is writing;2.has sent; 3.sends;4.will get;5.will bec.1.have seen;2.are buying;3.will buy;4.go;5.will seed.1.walked;2.walk;3.are walking;4.have just met;5.will walk;6.have walked
