Here, one can clearly determine the role of each noun in the sentence - “puellae” is in the nominative case, meaning that “the girls” are the subject of the sentence and the ones ran. “Ex” is the head of the prepositional phrase “ex cane,” which is in the ablative case, a case that, especially in this particular example, indicates motion away from some entity. Without this case system, it would be much more difficult to determine these roles and figure out exactly what is occurring in the sentence.
Although syntactic rules serve to clarify meaning, English sentences in particular can often contain ambiguity - humans tend to have predetermined expectations for language, so when faced with an ambiguous sentence, may interpret it differently than it was intended to be. For example, the classic “garden path” sentence “the horse raced past the barn fell” preys on these expectations - one may come to the verb “raced” and think that the sentence ends after “barn.” This initial ambiguity may be attributed to the fact that “the horse” is at the beginning of the sentence, causing the reader or listener to expect the horse to be running of its own accord and therefore resulting in confusion when they encounter the word “fell.” “Raced” is, in fact, a passive participle - the horse was being raced, with the verb “was being” omitted as it often is with sentences in the passive voice. Many other syntactically ambiguous sentences may result from a word’s ability to be used as multiple parts of speech, or can occur along with semantic ambiguity (when a word has multiple meanings and the reader cannot infer from context which one is