Issue with logic in homework

[fad3r]

Hi,
So my homework is to look at 3 strings. If the string has not before bad I am suppose to replace the everything between not and bad with good.

So the strings are:
This movie is not so bad
This dinner is not that bad!
This tea is not hot!

Should be:
This movie is good
This dinner is good!
This tea is not hot!

Here is my code. I can't figure out how change all three.

def not_bad(s):
    t = s.split()
    a = -1
    b = -1
    newlist = []
    newlist2 = []


    if "bad!" in t:

        for x in t:
            if x == "not":
                a = t.index(x)
            if x == "bad" or "bad!":
                if x == "bad!":
                    yellow = " good!"
                else:
                    yellow =" good"

                b = t.index(x)
        if a < b:
            newlist = range (a, b)

        for z in newlist:
            newlist2.append(z)
        newlist2.append(b)
        newlist2 = list(newlist2)
        newlist2.reverse()

        for take in newlist2:
            del t[take]

        t2 = ' '.join(t)
        t2 = t2 + yellow
        return t2
    else:
        t2 = ' '.join(t)
        return t2



print (not_bad("This dinner is not that bad!"))
print (not_bad("This tea is not hot!"))
print (not_bad("This movie is not so bad"))

I have played around a lot with trying to fix the first loop but no matter what I do either 2 or 3 is always wrong. Trying things like "bad or "bad!" just matches everything because of the article here: https://python-forum.io/Thread-Multiple-...or-keyword

So not sure how to check for both of them. If I could do that then everything would work.