How can I extract words from a file from a string

So I have tried to make it so that I can extract words in a file with every English word from random letters a generator gives me. Then I would like to add the found words to a list. But I am having a bit of a problem acquiring this result. Could you help me please?

This is what I have tried:

import string
import random

def gen():
  b = []
  for i in range(100):
    a = random.choice(string.ascii_lowercase)
    b.append(a)
    
    
    with open('allEnglishWords.txt') as f:
      words = f.read().splitlines()
      joined = ''.join([str(elem) for elem in b])
      if joined in words:
        print(joined)
      f.close()
  
  print(joined)

gen()

if you are wondering where I got the txt file it is located here http://www.gwicks.net/dictionaries.htm. I downloaded the one labeled ENGLISH – 84,000 words the text file

Answer

import string
import random

b = []
for i in range(100):
    a = random.choice(string.ascii_lowercase)
    b.append(a)
b = ''.join(b)

with open('engmix.txt', 'r') as f:
    words = [x.replace('n', '') for x in f.readlines()]

output=[]    
for word in words:
    if word in b:
        output.append(word)
print(output)

Output:

['a', 'ad', 'am', 'an', 'ape', 'au', 'b', 'bi', 'bim', 'c', 'cb', 'd', 'e',
 'ed', 'em', 'eo', 'f', 'fa', 'fy', 'g', 'gam', 'gem', 'go', 'gov', 'h', 
'i', 'j', 'k', 'kg', 'ko', 'l', 'le', 'lei', 'm', 'mg', 'ml', 'mr', 'n', 
'no', 'o', 'om', 'os', 'p', 'pe', 'pea', 'pew', 'q', 'ql', 'r', 's', 'si', 
't', 'ta', 'tap', 'tape', 'te', 'u', 'uht', 'uk', 'v', 'w', 'wan', 'x', 'y',
 'yo', 'yom', 'z', 'zed']