Is the following incomplete? The other mistakes of leaving off letters when using a word.

Question

Previous sentence: I have found that most can not properly spell or use the proper predicate.

Answer 1

The statement "The other mistakes of leaving off letters when using a word" lacks a predicate, so it is indeed an incomplete sentence.  "Leaving" may look like the predicate, but it is actually a gerund serving as the object of the preposition "of".  To make the fragment into a complete sentence, you need to add a predicate, such as:

 

The other mistake is leaving off letters when using a word.

 

or

 

Another mistake includes leaving off letters when using a word.