坚忍不拔

fortitude

strong / solid / firm / unyielding / resolute

persevering / tenacious

to bear / to endure / to tolerate / to restrain oneself

no; not so / (bound form) not; un-

to pull up / to pull out / to draw out by suction / to select / to pick / to stand out (above level) / to surpass / to seize