劳心苦思

to rack one's brains / to think hard

to toil / labor / laborer / to put sb to trouble (of doing sth) / meritorious deed / to console (Taiwan pr. [lao4] for this sense)

to work with one's brains / to rack one's brains / to worry

heart / mind / intention / center / core / CL:顆|颗[ke1],個|个[ge4]

bitter / hardship / pain / to suffer / to bring suffering to / painstakingly

to think hard / bitter thoughts / to pour out one's sufferings

to think / to consider