________about the exact address of the teacher,we had great trouble finding his flat
问题描述：
________about the exact address of the teacher,we had great trouble finding his flat
A Not being informed B Not having been informed
C Not having informed D Having not informed
答
选b
首先not应放在doing前；第二本句的意思是“我们未被告知”是被动句,所以要用be informed;第三注意后面句子用的是过去式had,所以要用having been done