BistBosworth & Toller 盎格鲁-撒克逊古英语词典 - bist根据古英语词典：bistart, shalt be; es, eris, Bd. 5, 19; S. 640, 43: Ælfc. Gr. 25; Som. 26, 28; 2nd pers. pres. and fut. of beón. bist