vowels = 'aieou' 
samepast = ['hit','cost','spread','cut', 'put', 'let', 'hurt', 'quit', 'read', 'broadcast'] #List of words that are the same in both tenses
irrpast = {'go':'went', 'break':'broke', 'buy':'bought', 'sit':'sat', 'eat':'ate',
           'come':'came', 'sleep':'slept', 'see':'saw', 'pay':'paid', 'sing':'sang',
           'tell':'told', 'get':'got','teach':'taught', 'feel':'felt', 'hear':'heard' }
#Dictionary of irregular verbs and their irregular past forms

def isLikeTap(wd):
    longCons = 'xwy' #These are the letters you want to exclude
    vowelCount = wd.count('a') + wd.count('e') + wd.count('i') + wd.count('o') + wd.count('u')
    if vowelCount == 1 and wd[-1] not in vowels + longCons: #concatenate the two sets - easier than doing two "and" clauses
        return True
    else:
        return False

#Implemented getting past tense as a separate function
#Uses negative indexing to get the last characters of words
def getPastTense(w):
    if w in samepast: #checks simplest case first
        past = w
    elif w in irrpast:
        past = irrpast[w] #gets irregular form from the dictionary
    elif isLikeTap(w) == True:
        past = w + w[-1] + 'ed'
    elif w[-2] not in vowels and w[-1] == 'y':
        past = w[:-1] + 'ied' #string slicing to get everything except the last character - w[:-1] is the same as w[0:-1]
    elif w[-1] == 'e':
        past = w + 'd'
    else:
        past = w + 'ed'
        
    return past #returns the past tense string I've built up

prompt = raw_input('What are your verbs? (Type EXIT to quit): ') #Starts off the prompting

while(prompt != 'EXIT'):
    words = prompt.split() #splits the words given into a list so it can work on each one
    for w in words:
         past = getPastTense(w) #calls the past tense function - just like calling a built in function!
         print w, past
    prompt = raw_input('What are your verbs? (Type EXIT to quit): ') #Have to put this here to continue the loop


print "Thank you for using the Past Tense Generator. Goodbye."