不可直接加形容词.
besides 是副词和前置词：
副词
加之,更,又,还有,而且；另外.
I am too tired to go,(and) besides,it is late.我不去了,太累啦,而且时候又晚了.
They had a roof over their heads but not much besides.他们除了住房,此外就没有什么财产.
前置词
1.在…之外(还有),…之余兼.
2.除…外(不再有).
There's no one here besides Bill and me.
我们有时看到
Besides smart Mary is also beautiful 这种句子.
表面上看好似 besides 接了形容词,但句子实际上是
Beside (being) smart ...
smart 前面有个现在分词.