(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 noun is a noun that is made up of two or more words. Most compound nouns in English are formed by nouns modified by other nouns or adjectives. For example: The words tooth and paste are each nouns in their own right, but if you join them together they form a new word-toothpaste.