艰苦卓絶

Explanation: Extreme hardship. Mao Zedong, "Rectify the Party's work style": "Hundreds of thousands of party members, they are leading the people toward the enemy and bitter struggle." Ling "Du Wan deeply rooted": "people who are the most admired man? Is epoch, great suffering, perseverance, struggle to win from, from the struggle of people to enjoy the fun of the Great Northern Wilderness. "