serious attempt serious attempts serious attention serious attitude serious attitude problem serious back serious bacterial serious bad serious barrier serious battle serious beating serious birth defects serious bleeding serious blood serious blow serious bodily serious bodily harm serious bodily injury serious book serious boy serious boyfriend serious brain serious brain injury serious breach serious breaches serious budget serious bug serious burn serious burns serious business serious but not serious but stable serious buyer serious buyers serious can serious candidate serious car serious car accident serious cardiac serious cardiovascular serious career serious case serious cases serious cash serious casualties serious cause serious cause for concern serious causes serious challenge serious challenges serious change serious changes serious character serious charge serious charges serious chat serious chronic serious clinical serious coin serious collector serious commitment serious company serious competition serious competitor serious complaint serious complication serious complications serious concern serious concerns serious concussion serious condition serious condition called serious condition that can serious conditions serious conflict serious conflicts serious consequence serious consequences serious consideration serious constraint serious contender serious conversation serious conversations serious corruption serious crash serious crime serious crimes serious crimes committed serious crimes unit serious criminal serious criminals serious crisis serious criticism serious cross-border serious crush serious damage serious danger serious dangers serious data