毛 * * 明确提出执政党建设的问题是在

A．中共七大

B．七届二中全会

C．七届三中全会

D．中共八大

"They didn’t take measures in time, otherwise the explosions ____．"some experts said．

A．wouldn’t happen

B．didn’t happen

C．wouldn’t have happened

D．mustn’t have happened