Answer:
In Paris but not in France the thinnest of its siblings.
The more of me there is the less you see.
I am of several different kinds, but the one you pick doesn't do its job. What am I?
It's red liquid but not liquid and it's not red. What is it?
People see through me, but none pass through without killing me. I can be anywhere, and can be seen double or single. What am I?
What language does a billboard speak?