Question

17. To his joy,the admission notice for         long arrived finally. (wait)

让他感到高兴的是，那封让他久等的录取通知书终于来了。

Answer 1

17. which he had been waiting考査关系代词作介词宾语时定语从句的用法。wait for等待。"让他久等的"的对应英文表达为定语从句。"the admission notice"是wait for的宾语。由于介词前移，此处关系代词只能用which。由于是"久等的"，所以用过去完成进行时。