3rd person singular English

def conjugate_pres_simple():
    for line in infile:
        print line[-3], line[-2]
        if line[-2] == "y" and not line[-3] in "aoue":
            outfile.write(line.rstrip("y\n") + "ies" + "\n")
        elif line[-2] in "shzx" and not line [-3] == "g":
            outfile.write(line.rstrip("\n") + "es" + "\n")
        else:
            outfile.write(line.rstrip("\n") + "s" + "\n")