public List<Chunk> findVerbChunk(SenData sen) {
        List<Chunk> ls = new ArrayList<>();
        int i = 0;
        Chunk c, prev = null;
        while (i < sen.chunks.size()) {
            c = sen.chunks.get(i);
            if (c.type.equals("VP") && !appoSet.contains(c.txt)
                    && !(prev != null && subclauseSet.contains(prev.txt) && prev.type.equals("NP"))) {
                if (getVerbChunkType(c, sen) < 2 && !c.txt.startsWith("as ")) { // skip VB+ing and To VB
                    ls.add(c);
                }
            }
            prev = c;
            i++;
        }
        return ls;
    }