serious public health serious punishment serious purpose serious quality serious question serious questions serious ramifications serious reaction serious reactions serious reason serious reasons serious reflection serious reform serious relationship serious relationships serious repercussions serious request serious research serious reservations serious resistance serious respiratory serious response serious responsibility serious results serious right serious risk serious risks serious rival serious road serious role serious roles serious safety serious sam serious sanctions serious science serious scientific serious scientist serious security serious setback serious setbacks serious shock serious shortage serious shortcomings serious side serious side effect serious side effects serious signs serious sin serious sins serious situation serious situations serious skills serious skin serious skin reactions serious social serious social problem serious social problems serious source serious state serious step serious steps serious story serious stroke serious structural serious student serious students serious study serious stuff serious subject serious subjects serious surgery serious symptoms serious systemic serious talent serious talk serious task serious tax serious technical serious test serious than i serious than i thought serious the situation serious therapy serious there serious thing serious things serious thinking serious this time serious thought serious thoughts serious threat serious threat to human serious threat to public serious threats serious time serious times serious to me serious to talk serious toll