同学你好，该知识点来自沪江网校《英语零基础直达大学六级【超值特惠班】》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~
3. sent to 寄给谁，这样比较通顺

B 1 He is the man we have heard so much about.
2 The shelf you put those books on has collapsed.
3 Who(m) did you receive a letter from?
4 This is the road we came by.
5 Where is the pencil you were playing with?

祝同学学习进步~