询问语法题动词填空Thebookstheauthor(print)weresoldoutlastweek.答案是hadhadprinted为什么是两个had?

Question

询问语法题 动词填空
The books the author _____(print)were sold out last week.
答案是had had printed
为什么是两个had?

Answer 1

过去完成时+被动语态,其中还有定语重句
the books that the author had had printed were sold out last week.
其中一个had 是have sth done句型,had the books ptinted,例如i have my hair cut