Sentence:  Never a `` quick study '' , he now made no attempt to learn his `` lines '' and many a mile of film was wasted , many a scene - sometimes involving as many as a thousand fellow thespians - was taken thirty , forty , fifty times because Miss Poitrine 's co-star and `` helpmate '' had never <WSD>learned</WSD> his part . 
Meaning of the word marked with <WSD> tags:  commit to memory; learn by heart