Grep（或可能正则表达式）在匹配之前或之后检查线条上的图案

I have a simple grep command that returns lines that match from a file. Here's the problem: Sometimes, when a line matches, I want to include the line before it. What I want is a way to find all the lines that match a pattern, then use a different pattern to see if the line before each of those results match.I have a simple grep command that returns lines