it takes two to tango. (99下~week13)

(1) idiom:  It takes two to tango. (一個巴掌拍不響）
(2) meaning: both people involved in a bad situation（狀態） are responsible（負責） for it.
(3) example: She blames（責怪） Judy for starting the quarrel（爭吵）. Well, it takes two to tango.