473. Rosario ______ on the problem at length, but no amount of extended reflection could provide her with a satisfactory solution.
A. collaborated
B. extemporized
C. expounded
D. expostulated
E. ruminated
474. Because Russell was such a memorable and public speaker, many people mistook his ability to talk about a wide range of topics for genuine .
A. enervating, inquisitiveness
B. charismatic, animosity
C. fluent, evasiveness
D. daunting, diffidence
E. adroit, erudition