1. As an versatile particle in English, "as" can act as an adverb, conjunction, preposition, and relative pronoun. Here is a summary of various clauses introduced by "as" for reference.2. Clauses indicating comparison, meaning "like," "just as," or "similar to": - "She's very tall, as is her mother." (She is tall, just like her mother.)3. Clauses indicating manner, degree, or situation, implying "in the way of," "like," or "as": - "They did as I had asked." (They acted in the manner I requested.)4. Clauses indicating time, meaning "when," "while," or "as": - "As he grew older, he gained in confidence." (As he became older, his confidence increased.)5. Clauses indicating reason, implying "because" or "due to": - "As you were out, I left a message." (Because you were out, I left a message.)6. Relative clauses introduced by "as": a) Non-restrictive relative clauses often referring to the whole of what the main sentence expresses and can be placed at the beginning, middle, or end of the sentence:- "Child as he is, he can tell black from white." (Although he is a child, he can distinguish between black and white.)- "Happy as they were, there was something missing." (Although they were happy, something was missing.) b) Restrictive relative clauses:- "From every corner of the island, little people came to see the 'Man Mountain' as they called Gulliver." (Little people from every corner of the island came to see Gulliver, whom they called the 'Man Mountain.') c) "As" used with "such," "so," or "the same" often refers to a specific noun, and "as" can act as a subject, object, or predicate in the relative clause:- "The book is written in such easy English as beginners can understand." (The book is written in easy English that beginners can understand.)- "She studies in the same department as I do." (She studies in the department that I am in.)- "Here is so difficult a problem as none of us can solve." (Here is a problem so difficult that none of us can solve it.)