See http://www.italki.com/answers/question/33837.htm THO is the same as THOUGH. THOUGH ; EVEN THOUGH. –Conjunction 1. (used in introducing a subordinate clause, which is often marked by ellipsis) notwithstanding that; in spite of the fact that; although; Though he tried very hard, he failed the course. 2. even if; granting that (often preceded by even). (EVEN THOUGH) –Adverb 3. for all that; however. —Idiom 4. as though, as if: It seems as though the place is deserted. ALTHOUGH –conjunction in spite of the fact that; even though; though. —Synonyms notwithstanding (that), even if, albeit (that). Usage Note: As conjunctions, although and though are generally interchangeable: Although (or though) she smiled, she was angry. Although is usually placed at the beginning of its clause (as in the preceding example), whereas though may occur elsewhere and is the more common term when used to link words or phrases, as in wiser though poorer. In certain constructions, only though is acceptable: Fond though (not although) I am of sports, I'd rather not sit through another basketball game.

This may help you: http://www.2zoo.org/uploads/13461492701.jpg Reference: New English File / Upper-intermediate / Student book