Mack knew this passage by heart.麦克会背这一段。You must keep repeating the lines until they are known by heart.你必须反复朗读这几行一直到能背诵为止.The boy learned the poem by heart.这男孩背下了这首诗....

凭记性...

by heart的音标：by heart的英式发音音标为：[bai hɑ:t]by heart的美式发音音标为：[baɪ hɑrt]...