stock-in-trade
noun [ U ] uk/ˌstɒk.ɪnˈtreɪd/ us/ˌstɑːk.ɪnˈtreɪd/
典型特点；典型行为；惯用手法
the typical characteristics or behaviour of someone or something
The song was perfect for the soft vocals that are her stock-in-trade. 这首歌非常适合用她最为擅长的柔声唱法演唱。
old-fashioned（某项工作的）用具设备
the tools and other objects that you need for your job