Avoiding Sentence Fragments

A sentence needs to have a subject and verb.

My cat has long whiskers.

If you have just a subject, or just a verb, you have a sentence fragment.

My cat.

Has long whiskers.

You can fix a sentence fragment by adding what is missing.

My cat has long whiskers.

Also, if a group of words does not express a complete thought, it is a fragment.

Because my cat has long whiskers.