Study hard, or you will fail.

Explanation

The sentence "Study hard, or you will fail" is a complex sentence because it:- Has an independent clause (Study hard)- Has a dependent clause (or you will fail)- The dependent clause is introduced by a subordinating conjunction (or)The sentence can be broken down into:- Independent clause: "Study hard" (stands alone as a complete sentence)- Dependent clause: "or you will fail" (cannot stand alone as a complete sentence)- Subordinating conjunction: "or" (connects the dependent clause to the independent clause)Complex sentences have a main clause and a subordinate clause, and this sentence fits that structure.