#!/usr/bin/env python3

import re

x = 'Confirmatory factor analysis (CFA)  is a special case of what is known as structural equation modelling (S.E.M.).'
results = []
split_regex = re.compile(r'\s+')
for m in re.finditer(r'\b([A-Za-z][a-z]*(?:\s[A-Za-z][a-z]*)+)\s+\(((?:[A-Z]\.?){2,})\)', x):
    abbreviation = m[2]
    l = sum(c.isalpha() for c in abbreviation)
    full_form = ' '.join(split_regex.split(m[1])[-l:])
    results.append([full_form, abbreviation])
print(results)# your code goes here