private static void ReplacePOSTag(Tree t, MorphoFeatureSpecification morpho)
        {
            if (!t.IsPreTerminal())
            {
                throw new ArgumentException("Can only operate on preterminals");
            }
            if (!(t.Label() is CoreLabel))
            {
                throw new ArgumentException("Only operates on CoreLabels");
            }
            CoreLabel label = (CoreLabel)t.Label();
            Tree      child = t.Children()[0];

            if (!(child.Label() is CoreLabel))
            {
                throw new ArgumentException("Only operates on CoreLabels");
            }
            CoreLabel childLabel = (CoreLabel)child.Label();
            // Morphological Analysis
            string morphStr = childLabel.OriginalText();

            if (morphStr == null || morphStr.Equals(string.Empty))
            {
                morphStr = label.Value();
                // POS subcategory
                string subCat = childLabel.Category();
                if (subCat != null && subCat != string.Empty)
                {
                    morphStr += "-" + subCat + "--";
                }
                else
                {
                    morphStr += "---";
                }
            }
            MorphoFeatures feats = morpho.StrToFeatures(morphStr);

            if (feats.GetAltTag() != null && !feats.GetAltTag().Equals(string.Empty))
            {
                label.SetValue(feats.GetAltTag());
                label.SetTag(feats.GetAltTag());
            }
        }