解：$$\square +\square +\square +\triangle +\triangle +\triangle =27$$，  得$$\square +\triangle =9$$①，  $$\triangle +\triangle +\square =12$$得$$2\triangle +\square =12$$②，  ②$$-$$①得：$$\triangle =3$$，  把$$\triangle =3$$代入①得：  $$\square =6$$  故选：D。 
下式中，$$\square $$和$$\triangle $$分别代表（  ）  $$\square +\square +\square +\triangle +\triangle +\triangle =27$$  $$\triangle +\triangle +\square =12$$。 
Options:
[a] $$3$$和$$4$$ 
[b] $$3$$和$$6$$ 
[c] $$4$$和$$6$$ 
[d] $$6$$和$$3$$ 