Hey all, short Finnish question

I came across this line

"Kokoomuuksen tilanne tietyllä tapaa hankala"

My problem here is that this sentence lacks the verb "to be". I know in many languages the verb "to be" is omitted often in the present tense, however in Finnish I have never seen this as the case. I asked my wife and she said that this is completely natural sounding however when I asked her if I could say something like "taivas sininen" or "me naimisissa" she said this was not allowed.

Could anyone explain this?

(oh and while I'm at it, in this sentence "se pitää tehdä", why isn't tehdä in the passive?)

Thanks!