def appear_only_at_sentence_beginning(word, title, sents):
    """
    if the token appears in the text only at the beginning of the sentences

    >>> title = [u"Feng", u"Chao", u"Liang", u"Blah"]
    >>> doc = [[u"Feng", u"Chao", u"Liang", u"is", u"in", u"Wuhan", u"."], [u"Chao", u"Liang", u"is", u"not", u"."], [u"Liang", u"Chao", u"is", u"not", u"."]]
    >>> appear_only_at_sentence_beginning(u"Feng", title, doc)
    True
    >>> appear_only_at_sentence_beginning(u"Chao", title, doc)
    False
    >>> appear_only_at_sentence_beginning(u"Blah", title, doc)
    False
    """
    assert (word in title), "The word should be a title word"
    appear_at_sentence_beginning = False
    
    for sent in sents:
        sent_start = True
        for w in sent:
            if sent_start and w == word and word[0].isupper():
                appear_at_sentence_beginning = True
            elif w == word: # appeared cap in the middle of sentence
                return False
            sent_start = False
            
    if appear_at_sentence_beginning:
        return True
    else:
        return False