why 去掉用不到why 的意思why改为t ha t答案是that 加不加都行the reason that，，是同位语is 后是表语从句The regulation requires that everyone who holds a non-immigrant visa reports his address to the federal goverment in January of each year哪里错了！详细解析一下！谢谢了求快在英语中,表示"建议 要求 命令 "等意义的动词后接宾语从句时 使用"should do"should 常被省略require that sb. shoud do