Read this: During the Soviet period, the policy toward the languages of the various other ethnic groups fluctuated in practice. Though each of the constituent republics had its own official language, the unifying role and superior status was reserved for Russian, although it was declared the official language only in 1990. Following the break-up of the USSR in 1991, several of the newly independent states have encouraged their native languages, which has partly reversed the privileged status of Russian, though its role as the language of post-Soviet national discourse throughout the region has continued.

What unofficial status did Russian have in the USSR before 1990?
What is the answer? (If it cannot be answered, return "unanswerable")
the unifying role and superior status