"Are they tall trees?"
Translation:Jsou to vysoké stromy?
That is very strange, the agreeing modifier (adjective) should come before the modified noun.
In a declaration (here we have a question) one could say:
"Stromy jsou to vysoké."
However, that would put the adjective in the predicate. The trees are tall. Saying that as "Jsou to stromy vysoké." would be unnatural.