" "Unaware of what was behind the door" = an "adjective clause" I'm not sure if you want these broken down more specifically, but that is the general answer.
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AnonymousUnaware of what was behind the door, he pushed the door hard to get in.Terminology varies from country to country. I'm sure this is of no avail to you since you probably live in an English speaking country, but I'll tell you anyway that the underlined part is called a causal clause equivalent where I live.