If you could look inside a pre-synaptic axon terminal, you would find one of the characteristics is that it's loaded with these vesicles and they're just sitting there waiting to receive an action potential so that they can immediately dump their contents.

如果你能够一窥突触前的轴突末梢内部,你将会发现一个共同特征,神经递质都装载在小泡中,时刻准备着等待动作电位激活,以便迅速释放其内含物

耶鲁公开课 - 生物医学工程探索课程节选

One day I was sitting there at iTunes and I wanted to buy an interior movement of a Mozart serenade so I was all set to purchase this and it said, "Buy song." Boom.

有天我在苹果的iTunes音乐商店,想买首莫扎特小夜曲,它属于室内乐,我准备买下时 网页上显示,"购买歌曲"

耶鲁公开课 - 聆听音乐课程节选