import re


def normalize_en(s):
    """ Processes an English string by removing non-alphabetical characters (besides .!?).
    """
    s = s.lower().strip()
    s = re.sub(r"([.!?])", r" \1", s)
    s = re.sub(r"[^\w.!?]+", r" ", s, flags=re.UNICODE)
    return s