Just out of impulse, he shot the duck in the head and killed it.

他一时冲动，朝鸭子的头开了一枪，把它打死了。

Retailers like them as they add a dash of colour and buzz to shops, and because they can squeeze more money out of each customer through impulse purchases.

零售商们喜欢促销，因为这样可以给商店带来一些生机，而且还能通过消费者的冲动购买榨取更多钱。

That explains the Pavlovian impulse of people who are out with friends or dates to ignore them and check their BlackBerrys and cellphones, even if 99 out of 100 messages are uninteresting.

这解释了人们的“巴甫洛夫冲动”，他们在跟朋友外出或者约会时也会忽略对方，却不断查看他们的“黑莓”和手机，即使 99% 的短信都是无趣的。