adverb
BAD : She spoke very shortly about how they had lived during the war.
GOOD : She spoke very briefly about how they had lived during the war.
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shortly = (1) impatiently; not politely: 'He answered rather shortly that he was NOT the slightest bit interested.' (2) very soon: 'The accident happened shortly after they moved into their new house.'
briefly = for a short time: 'We talked briefly about the financial side of the agreement and then moved on to other matters.'