AS

"As" se puede usar de diferentes maneras:
- para presentar una profesión o trabajo: She works AS a nurse
- para comparar gente o cosas: She's AS tall AS me now
- para hablar de cómo algo suena, siente, parece...: AS IF (como si): it looks as if  it's going to snow
- para aportar una CAUSA: AS it was raining, we didn't go out
- para decir que algo pasa mientras (WHILE) algo ás está pasando: AS they were leaving the girl arrived
LIKE/AS: http://www.curso-ingles.com/aprender/cursos/nivel-intermedio/comparative-superlative/like-vs-as