The boy is so young that he can't dress himself 改为同义句The boy is too young to ( ) dress himself.

The boy is so young that he can't dress himself 改为同义句The boy is too young to ( ) dress himself.
The boy is so young that he can't dress himself 改为同义句
The boy is too young to ( ) dress himself.

The boy is so young that he can't dress himself 改为同义句The boy is too young to ( ) dress himself.
The boy is too young to dress himself 就是对的,不需要再加其他词

make

The boy is too young to dress himself.
So young is the boy that he can't dress himself.

我同意楼上的意见，空格处不填句子就已经完整，硬要加的话只能加一些修饰性的副词，但是这样的话就和原句的意思不一样了，所以楼主自己看吧，尽信书不如无书。