(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.
The predicate is the part of a sentence (or clause) which tells us what the subject does or is. To put it another way, the predicate is everything that is not the subject. At the heart of the predicate is a verb. In addition to the verb, a predicate can contain direct objects, indirect objects, and various kinds of phrases. A sentence has two parts: the subject and the predicate. The subject is what the sentence is about, and the predicate is a comment about the subject. Quick Video Here is a video summarizing this lesson on the term predicate: