-- you called yesterday?
-- Tom．Why?
A. Who it is that
B. Who is it that
C. Who was it that
D. Who it was that
网友回答
A. Who it is that
B. Who is it that
(答案→)C. Who was it that
D. Who it was that
解析：考查特殊疑问句的强调句型。结构为：疑问词+ is/was + it + that? 根据句意：昨天你究竟给谁打电话了？所以选C。