1.be friendly with 是和某人相处得好,与某人友好,跟某人做朋友...
He pretended to be friendly with me.
他假装对我友善.
2.be friendly to 对某人友好
Animals:Let us be friendly to each other,man!
动物是人类的朋友,让我们和谐相处.
to强调相对性,对某人,是具有主动性的,而with则是和某人,强调并列