be good with意为“灵巧的；与……相处得好”.
例如：
She is good with her hands.她手很巧.
He is very good with the children.他与这些孩子处得很好.
be good to意为“对……友好”.
例如：
My friend was good to me when I was ill.我生病时我的朋友对我关怀备至.