I think comprehension should also let you talk in any language even if you dont know it. what do you think?

But comprehension is about understanding, not production. For instance I fully comprehend how a nuke works, but I'm unable to produce one.

i see your point, as in a foregin person can undrestand english fine, but can not reproduce it well,.

Yeah, kinda like, I took spanish in school for 5 and a half years, and I can understand some of what people are saying, but it's still very hard for me to build sentence structure in order to say something myself.