"I didn't know you were looking for some new shoes." "Oh, I wasn't - I just bought them on impulse." “我不知道你想要买双新鞋。”“噢，不是的——我只是一时冲动才买的。”
She decided, on an impulse, to get in touch with some of her old classmates.
On an impulse, he went into the florist's and bought a huge bunch of roses.
He called Judy on impulse and invited her to lunch.
Acting on impulse, she grabbed her camera and ran after the man.
See also: impulse (WISH)