English: subject to change?

Question

These are subject to change.

I wonder why 'change' comes though 'subject is thing. I would say like this: These are subjec to be changed, as it seems like a passive voice.

Answer 1

The language is lazy
The full meaning would be 'these are liable to be subjected to a change'

Answer 2

Just add the word "things" and make it:
"These things are subject to change"--meaning that under the right circumstances, things could change or be altered.

Answer 3

In this usage, "suject to" probably means "liable to", "conditional upon" or something similar.