—Who can that be at the door at this hour?—______my neighbor. He often calls this late.

【正确答案】 C

【答案解析】解析：句意：——这个时候敲门的会是谁?——是我的邻居。他经常这么晚拜访我。本题考查的是it用作代词的用法。说话者不清楚性别时用it指代，故C正确。