stock-in-trade
/ˈstɒkɪnˈtreɪd/noun
mass noun
1- the typical subject or commodity a person, company, or profession uses or deals in（个人、公司、行业的）典型经营范围, 招牌商品：
information is our stock-in-trade.
信息是我们的主要经营范围。
1.1
- qualities, ideas, or behaviour characteristic of a person or their work（人或其工作的典型）特点, 思路, 行为：
flippancy is his stock-in-trade.
轻率是他的特点。
1.2
- the goods kept in hand by a business for the purposes of its trade库存品, 存货。