be adj to sb 与be adj for sb 区别

Question

Smoking is harmful to one's health
It is necessary for you to get there on time.

Answer 1

be adj for sb 是固定的 it is adj of/for sb to do sth
be adj to sb 是指对于某人 读一下就可以分辨了

Answer 2

be+（adj.)+to sb 是有对于的意思，
而be+（adj.)+for sb后面的sb一般是别人。