Help me understand how to conjugate the word sein

1.berlin was not a capital of all of germany for roughly 40 years after wwii. true false 2. true berliners are known to speak their mind openly. true false 3. the german parliament voted to reinstate berlin as the german capital of all of germany in 1991. true false 4. berlin is not the only capital, but also germany's largest city true false 5. people who speak the dialect of berlin do not follow german grammar rules closely. true false