“这就是我昨天买的这支笔”和“这就是我正在找的这本书”用英语中的定语从句怎么做

This is a pen that Ibought yesterday.这就是我昨天买的这支笔.This is a book that I'm finding it now.这就是我正在找的这本书.I didn't see the movie yesterday,because I have seen it twice.我昨天没有去看电...