He stared at me as if seeing me for first time.

He stared at me as if seeing me for first time.
as if 后面用ing形式表示似乎正在做某事
例如：He stood there as if waiting for someone.
He cleared his throat as if to say something.
as if 后面用to do形式表示似乎将要做某事
例如：He gave me a letter as if to leave here.