The error that makes the sentence wrong is the word of "Although." It makes the sentence like a fragment. It looks like it need another clause to make it a complete one.
Answer:
I'm happy is the answer for your question
Answer:
a) break, find, win, buy, swim, drink, drive, hold, know, think, make, meet, say, write
b) broke/broken, found, won, swam/swum, drank/drunk, driven/drove, held, knew/known, thought, made, met, said, wrote/written
