see A as B 结构中，as为介词，后接B构成介词短语作宾补。

B 可以是名词、动名词、过去分词、形容词等。但B为过去分词或形容词时，通常理解为过去分词或形容词前省略了动名词being.

Optimists see a glass as half full rather than half empty.

= Optimists see a glass as (being) half full rather than (being) half empty.

half在此为副词，修饰形容词full和empty. as介词短语为宾补动名词being被省略了。

A passive person is often seen as weak and easy to control.

= A passive person is often seen as (being) weak and easy to control.

这里being用或不用都是正确的，即being可以省略。本质上是介词as后接动名词短语，being被省略了可以加上。