某些气味会引起恶心，这是对无条件刺激的反应。

Certain smells can cause nausea, which is a response to an unconditioned stimulus.

食物是狗的无条件刺激，它会自动引起唾液分泌。

Food is an unconditioned stimulus for dogs, causing them to salivate automatically.

热水是手缩回的无条件刺激，因为它会引起疼痛。

Hot water is an unconditioned stimulus for withdrawing your hand because it causes pain.

宝宝看到妈妈的脸会笑，这是对无条件刺激的自然反应。

A baby smiles when seeing its mother's face, which is a natural response to an unconditioned stimulus.

当你听到响亮的声音时，你的惊吓反应是一种对无条件刺激的反应。

When you hear a loud noise, your startle response is a reaction to an unconditioned stimulus.

我们称食物为无条件刺激，我们称分泌唾液为无条件反射。

We call the food an unconditioned stimulus, and we call salivation the unconditioned response.

当无条件刺激与条件刺激同时出现时，经典条件作用的效果最强，两种刺激所引起的反应是相同的。

And so classical conditioning should be the strongest when these two are simultaneous and the response to one is the same as the response to the other.