Using regular expressions, how can we find all paragraphs of match type A NOT B

E.g Find all paragraphs which has the word "pattern" but doesn't have the word "regular".
So in the following text, 2 & 3 should be selected while 1 should be omitted:
1. With regular expressions you can describe almost any text pattern
2. including a pattern that matches two words near each other.
3. This pattern is relatively simple, consisting of three parts.