Difference (from prior major revision)
(author diff)
Changed: 9c9
Other expressions can have their meaning altered entirely by avoiding the split infinitive. The sentence "He failed to completely understand the book" suggests that the understanding is partial and not complete, whereas "He failed completely to understand the book" implies that no understanding was achieved at all. However the sentence "He failed to understand the book completely" conveys the same information as the one with the split infinitive.
Other expressions can have their meaning altered entirely by avoiding the split infinitive. The sentence "He failed to completely understand the book" suggests that the understanding is partial and not complete, whereas "He failed completely to understand the book" implies that no understanding was achieved at all. The other alternative "He failed to understand the book completely" is ambiguous, as it is not certain whether the adverb is attached to "failed" or to "understand".