liminal stimulus

例句：

1. 1.The researcher found that the threshold for detecting a chemical change was very low.
   研究者发现检测化学变化所需的阈值非常低。
2. 2.The threshold for a new drug to be approved by the FDA is high.
   新药被FDA批准的阈值很高。
3. 3. The threshold for a person to become addicted to drugs is often lower than we think.
   一个人对药物上瘾的阈值通常比我们认为的要低。