(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.
A compound word is simply two or more words joined to create a new word with a meaning different from any of the individual words. There are compounds nouns, adjectives, verbs, and adverbs. Words may begin as open compounds and over time evolve into hyphenated compounds and then to closed compounds.