my subWords method

public String subWords(String phrase, List<String> nouns, List<String> verbs, List<String> adj){
        String returnString = "";
        String[] result = phrase.split("\\s");
        for(String word : result){
            returnString += " ";
            if(word.equals("noun")){
                returnString += nouns.get(0);
            }
            if(word.equals("verb")){
                returnString += verbs.get(0);
            }
            if(word.equals("adjective")){
                returnString += adj.get(0);
            }
            if(!word.equals("noun") && (!word.equals("verb")) && (!word.equals("adjective"))){
                returnString += word;
            }
        }
        return returnString;
    }