撒网捕风

lit. the wind cannot be caught in a net / to waste one's effort (idiom)

wind / news / style / custom / manner / CL:陣|阵[zhen4],絲|丝[si1]

to let go / to cast / to let loose / to discharge / to give expression to / (coll.) to pee

to scatter / to sprinkle / to spill

net / network

to catch / to seize / to capture

to throw a net