[译] 老师要求每个学生在星期五以前交论文。
[误] The teacher required that every student must hand in his paper before Friday.

[正] The teacher required that every student should hand in his paper before Friday.
[注] 根据 require 的用法要求，如果其宾语是 that 从句时，从句中的谓语动词应该用虚拟语气，即"should + 动词原形"。require 和 request 在跟 that 从句时，从句中的谓语动词均用虚拟语气，表示的意思也很相似，区别在于：require 含有"要求履行"的，尤指行为；而 request 表示"请求"，是比较正式而有礼貌的用语。