在赌场里，他尝试使用加倍下注策略，但很快就输光了所有筹码。

At the casino, he tried the ___martingale strategy but quickly lost all his chips.

驯马师检查了马匹的马具，确保颈带系得牢固。

The trainer checked the horse's harness to make sure the ___martingale was securely fastened.

在概率论中，鞅是一个重要的数学概念。

In probability theory, a ___martingale is an important mathematical concept.