a simple sentence is a sentence consisting of only one dependent clause, with a single subject and predicate. for example ¨The train was late¨ is a simple sentence.
A compound sentence has at least two independent clauses that have related ideas. The independent clauses can be joined by a coordinating conjunction . for example 'This house is too expensive, and that house is too small.'
Complex sentences contain an independent clause and at least one dependent clause. An independent clause has the ability to stand alone as a sentence. for exaple ¨Although Denise had some doubts, she found the courses very useful.¨
A compound-complex sentence is made from two independent clauses and one or more dependent clauses. for example ¨Though Mitchell prefers watching romantic films, he rented the latest spy thriller, and he enjoyed it very much.¨