問題詳情：
—What has made him so upset recently?
—________alone to face a troublesome milk case.
A．Left B．Being left
C．Having left D．To leave
【回答】
B 考查非謂語動詞的用法。下句是省略回答，補充完整為：Being left alone to face a troublesome milk case has made him so upset recently.所以下句的省略回答僅是what所指內容，充當主語，所以用動名詞作主語(注意被動關係)。
知識點：非謂語動詞
題型：選擇題
