单选题
The marketing team members stayed behind as everyone else left the conference room as they had matters to discuss by ______.
【正确答案】
A
【答案解析】[解析] 语法：代词
1．这是一道与人称代词的格有关的题。介词by后接反身代词意为“独自、自己”。
2．在语义上，on their own=by themselves。因此C选项如将by their own改成on their own即为正确选项。