aww thanks
it's best to ask them to repeat, pray to god that they'll rephrase/say it slower, and if that fails, just answer what you think is right. although i've done that a few times with the language assistant, and sometimes she'll stop, look to the right, purse her lips and go "uh-uh". very demoralising, lol. they'll probably just mark you down for not understanding the question fully, but it's better than having an awkward pause and still getting the question wrong, in my opinion.
although when i first started practicing my DS with the language assistant, she liked asking __どしたらいいですか。i had no idea what it meant, so i guessed she was asking 'what is good' rather than 'how to make it good/better'. so while i understood a tiny part of it (sort of?), i'd still misconstrued the question and gotten it wrong.
or maybe, you could use aizuchi to clarify the question if you're not sure? e.g. take out a key word, and go 'keywordですか'. that might help in making sure you're on the right track