Complete each sentence with a suitable word.

{"q": "I believe that experiments ___ animals should be banned.", "a": "on"}, {"q": "After ___ while, we decided to stop exercising and have a rest.", "a": "a"}, {"q": "Sarah has always been curious ___ space exploration.", "a": "about"}, {"q": "The scientists wanted to see ___ their theory was true.", "a": "if"}, {"q": "Rick came ___ the conclusion that we needed more time to finish the project.", "a": "to"}