The report urged that all students ----- to use computers.A.

答案为 C,用be 动词原形,由主句的谓语动词 urge 决定,属于“指使、命令、建议”类,类似的动词还有order,suggest(建议）,insist(坚持要求）,recommend,command,require等.此类动词的宾语从句一律用动词原形do (主动）或be +done（被动）如：
Our teachers require that all students hand in homework on time.
由此衍生的主语从句、同位语从句亦要求动词原形do (主动）或be +done（被动）如：
It is required that all students hand in homework on time.
It is a requirement that all students hand in homework on time.