单选题 The conversation had been carried on chiefly in French, a language which Mr. Steward was perfectly acquainted.
A. carried on
B. in French
C. which
D. perfectly

【正确答案】 C
【答案解析】改为with which。因为which所代表的先行词language在定语从句中是be acquainted with后的宾语，此处with不可省略，故放于which前。