http://www.esltower.com/GRAMMAR....hen.swf ->>> Сonjunctions SO, UNTIL, BECAUSE, WHEN
http://www.esltower.com/GRAMMAR....ing.swf ->>> Using conjunctions WHILE & DURING. "While" is used with a subject and a verb. While I was playing with my cat, my sister was doing her homework.
During -The preposition "during" is used to represent the length of time of an action that is while the action is happening.
"During" is used with a noun/pronoun (or any other form of nouns).
http://www.esltower.com/GRAMMAR....ago.swf ->>> Using conjunctions SINCE, LAST, AGO
http://www.esltower.com/GRAMMARQUIZ/intermediate/for%20or%20since.swf ->>> Using conjunctions FOR or SINCE in present perfect tenses.