One of the main difficulties that students of specialized languages are faced with is understanding those texts in which premodification and postmodification structures are frequently used. Understanding a written text is a fundamental activity for students of EAP and EOP; in fact, in many cases it is a prior activity on which other exercises, such as composition, translation, rewriting, oral practice of the language, etc. are based. These are the reasons why, from the point of view of modification, this paper analyzes some typical errors in comprehension that students make, and a few strategies and examples of exercises are also presented in order to make their comprehension and application easier. The study group that was analyzed consists of university students from "Economic Translation," "Scientific-Technical Translation," and "English for a Specific Purpose: Tourism," all having an upper-intermediate level of English. The texts used are authentic and belong to the various genres of this field.