(February 2013) Durham tubes are used in microbiology to detect production of gas by microorganisms. They are simply smaller test tubes inserted upside down in another test tube. This small tube is initially filled with the solution in which the microorganism is to be grown.
A compound predicate is two or more simple predicates joined by a conjunction that indicate actions by the same subject. Example : Bill picked up the mail and walked the dog.. Bill is the subject for both verbs.
Moving even higher on the ladder of sentence complexity, we've got the complex-compound sentence. As you might have guessed, complex-compound sentences are a combination of compound sentences and complex sentences. They have at least two main clauses and one dependent clause, and sometimes many others. Punctuation can also expand past the lone comma and period to include semicolons, and even dashes.