【题目】When first to the market, these products enjoy great success.
A. introducing B. introduced C. introduce D. being introduced
在线课程【答案】B
【解析】
试题考查被动语态。完整形式为when (these products were) first introduced to the market,作时间状语从句，为避免主语重复省略括号内容。句意：这些产品初次被引进市场就取得了巨大成功。故选B。