For,since,already,yet.

How many answers can you get right? Do the exercises online and improve your English. You will be self-corrected.

http://www.montsemorales.com/gramatica/PresPerfpartic.htm

http://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-17335.php

http://www.grammar.cl/Games/For_Since.htm

http://www.englishexercises.org/makeagame/viewgame.asp?id=2705