对症下药（對症下藥）　

◎ 对症下药 duìzhèng-xiàyào

[suit the medicine to the illness;(fig) suit the remedy to the case;prescribe the right remedy for an illness] 原指医生针对病情处方用药,现在常用来比喻针对具体情况决定采取措施或处理办法

你要老实把原因告诉我,我才能对症下药