GMAT question( which one is correct)Although they were sold/they were selling them over the counter at the turn of the century, the government now prohibits the sale of cocaine derivatives.
网友回答
they were sold
they 代名词,指的就是后句中的 cocaine derivatives
用被动语态过去时 were sold 表达 “曾经被当作非处方药物贩卖”
over the counter 是美国药房对于“非处方药品”的专用术语.
======以下答案可供参考======
供参考答案1:
尽管世纪之交时可卡因派生物在柜台上被买卖，但现在政府禁止这种交易。 选they were sold。