海底捞月: try to fish out the moon from the bottom of the sea - - strive for the impossible [illusory]; a fruitless attempt; a useless effort; cry for the moon; dredge for the moon in the sea; fishi
竹篮子打水一场空: draw water with a bamboo basket -- achieve nothing; draw water with a sieve; pour water into a sieve; all in vain; draw water with a sieve -- fruitless labor
假设终究只是一场空: how it could be now or might have beenhow it should be now or might have been