这是虚拟语气
对于表建议,要求的一些词,比如suggest,require,insist,desire 在名词性从句中,（本句是require),要用虚拟,后面用should + 动词原型,但是,should 可以省略
但是,此句的complete 应该是被动,should be completed
the financial information( presented to them by mortgage applicants )为information 的定语
框架就是,bankers require that information (should )be completed