1. A computer-readable non-transitory storage medium containing a classifier conversion application that, when executed, causes a computer to perform a method that converts an extant host language classifier on the computer to an initial target language classifier, the method comprising: translating marked host language examples included in the extant host language classifier on the computer to obtain translated marked target language examples, each example being an informational pair of a feature or features of the respective language and a classification result for that feature or feature; building an initial target language classifier using the translated marked target language examples; marking un-marked target language examples from passages of target language text using the initial target language classifier in order to obtain marked target language examples; re-classifying the marked target language examples in the initial target language classifier; questioning the marking used to obtain the marked target language examples in the initial target language classifier based on the re-classifying; isolating a high-quality set of marked target language examples based on the results of the questioning; and using the high-quality set of marked target examples to improve the initial target language classifier.