1.little此种用法少见,此时其位置一般放在谓语动词之前,即一般为：
They little know what his trouble is.
She little dreamt that she would marry him.
2.不过此时句子采用部分倒装语法常见,即最好为：
Little do they know what his trouble is.
Little did she dream that she would marry him.
3.二楼的写法其实是视little为代词.