At every party, Helen attended that year he'd keep coming back again like a bad penny. 那一年，海伦参加晚会，没有一次不见到他，觉得很讨厌。
The conditioned response, once it is firmly established, can be extinguished dozens of times, but it will always return, like the proverbial bad penny. 条件反射一经形成，虽然可以一次又一次地压制下去，但是它总会重新再现，真是摆也摆不脱扔也扔不掉。
He kept turning up like a bad penny at every party. 没有哪次晚会见不到他，真令人讨厌。
