To understand the grammar of the sentence, you must break it       into parts. 

I can’t thank you ________ much because without your help I ________ have won the first prize.

We were late, ________ the film wasn’t very good.

As he works in a remote area, he visits his parents only _______ .

His parents，_________，did not look after him very well—the elbows of his jacket were patched and his boots were badly worn.