絞盡腦汁

to rack one's brains

to twist (strands into a thread) / to entangle / to wring / to hang (by the neck) / to turn / to wind / classifier for skeins of yarn

to use up / to exhaust / to end / to finish / to the utmost / exhausted / finished / to the limit (of sth) / all / entirely

brain / mind / head / essence

brains

juice