易守难攻

easily guarded, hard to attack

difficult (to...) / problem / difficulty / difficult / not good

disaster / distress / to scold

to guard / to defend / to keep watch / to abide by the law / to observe (rules or ritual) / nearby / adjoining

easy / amiable / to change / to exchange / prefix corresponding to the English adjective suffix "-able" or "-ible" / abbr. for 易經|易经[Yi4 jing1], the Book of Changes

to attack / to accuse / to study