(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 phrasal compound is a group of words that express a complex  meaning, but are not formed through the usual noun or verb  modification. They may be idiomatic phrases, such â¦ as middle of the  road.. Or they may, because of the varied uses of the words, have  more than one meaning.