I want to know the answer to the following question:
When did Eduard Shevardnadze gain full membership in the Politburo?
All the background I'm provided with is that "Also on July 1, Gorbachev took the opportunity to dispose of his main rival by removing Grigory Romanov from the Politburo, and brought Boris Yeltsin and Lev Zaikov into the CPSU Central Committee Secretariat.". Is that enough to answer the question?
Answer: no