同学你好，该知识点来自沪江网校《新概念英语2、3、4册连读【双11专享班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~
这是个常见的搭配，可以固定这么使用。
There was a time when Charles was coasting at school and I should have told him to buckle down.
有一段时间查尔斯在学校不太用功，我当时应该让他加把劲的。
There was a time when each teacher spent an hour, one day a week, testing pupils in every subject.
曾经，每个老师每周都有一天花上一小时对学生的每门功课进行测试。

祝同学学习进步~