Detailed Instructions: You are given an English sentence with a blank, and you need to predict the missing word. After completing, the whole sentence should be gramatically correct and non-ambiguous.
Q: she said she hadn't time to get sick watching to see that i didn't fall overboard she said she never saw the beat of me for prowling about but if it kept her from being seasick it's a mercy i did prowl isn't it and i wanted to see everything that was to be seen on that boat ____ i didn't know whether i'd ever have another opportunity
A:
because