有一读者问： 有这样两个句子：
(1)The sellers agree to sell the goods subject to the terms and conditions as stipulated hereinafter.
(2)Should the named vessel arrive earlier than the date of arrival as previously notified to the sellers, the buyer shall advise the sellers in time.
如何解释以上两句中的“as+过去分词”?
“as+过去分词”是一种省略被动结构，连词as（意为“如同，按照”）之后省去了“主语+助动词be”。具体到上述句（1）和句（2），前者的as之后省去了they are, 后者的as之后省去了it was。这种“as+过去分词”结构常可遇到，尤其在书面语中，再如：
(3)Everything had happened exactly as expected . （as后省去it had been）
(4)He said that he would apologize to the worker if the facts were as stated . （as后省去they were）
“as+过去分词”之后可接表施动者的by短语，如：
(5)Socrates' conversations as reported by Plato were full of a shrewd humour. （as后省去they were）
顺便提一下，还有一种“关系代词as（本身无意义）+过去分词”省略被动结构，其中as之后省去了助动词be，如：
(6)Doctors may prepare, as required , sticks ranging from 0.23m to 0.5m in length. （as后省去is）
上述两种“as+过去分词”省略被动结构形式上虽然相同，但其语法结构大不一样。二者切切不可混淆。
