医生告诉我妻子，我有一半的生存机会。

The doctors told my wife I had a fifty-fifty chance of ___survival.

他主要关心的是确保自己的政治生存。

His main concern is to ensure his own political ___survival.

对许多动物来说，动物园是它们生存的唯一希望。

For many animals, zoos are their only hope for ___survival.