regexp match string with word1 and not word2

[Flyzone]

James Stroud ha scritto:

> The P.S: suggests homework, but this can't be homework because python
> regex won't do this, so your teacher gets an F if its homework. You

Not a homework, but a "workwork" :-)
I'm writing a script to parse logfiles, and I have began to study
python for this (bash was too much slow).
When i'll finishi it, I'll post a link here if someone think that
could be helpful.

> require a negative look-behind assertion of variable length--not
> possible in python regex. You will have to use something else--or maybe
> you don't understand the homework problem.

I was asking that cause in the code i wrote this:
      for y in range(0, len(skip_lst) ):
                 if (re.search(skip_lst[y], line)):
                              skip=1
                               break

In skip_lst there are the regexp and strings (on one line) to match
with "line".
But rarely the rules to be matched need to have also a logical And.
What could be the solution? Add another array with a "not" regexp?