http://sana.tkk.fi/awe/cohesion/signposts/contrast/exercises/selectbox1.html

http://www.englishexercises.org/makeagame/viewgame.asp?id=1792

http://www.englishdaily626.com/sentence_connectors.php?005

http://pt.scribd.com/doc/19128733/Exercises-on-Connectors

http://a4esl.org/q/f/y/zz99maa.htm