将以下这段文本总结至100字，且需要保留核心观点和主要数据：  
ikhail Gorbachev, the last leader of the Soviet Union, led the country through a turbulent time, implementing policies of glasnost (openness) and perestroika (reform), both aimed at modernizing the Soviet system. Despite these reforms, they failed to stabilize the economy or prevent the eventual collapse of the USSR in 1991. Gorbachev's efforts to open up Soviet society and politics were groundbreaking, but his inability to manage the rapid changes and mounting political pressures led to his political downfall and resignation in December 1991. Gorbatchev的政策在当时被视为具有前瞻性和勇气，但最终并未达到预期的效果。
user
戈尔巴乔夫作为苏联最后的领导人，通过实施透明化和改革政策试图现代化苏联体系。尽管这些改革具有前瞻性和勇气，但未能稳定经济或避免苏联在1991年的解体。最终，戈尔巴乔夫因未能有效管理快速变化和政治压力而于1991年12月辞职。
assistant