It was Mr Green looked after my grandmother when I was on business.
A. whom
B. which
C. whose
D. who
网友回答
A. whom
B. which
C. whose
(答案→)D. who
解析：考查强调句型。强调句型的基本结构：it is/was被强调成分that/who其它成分；最大的特点是把it is/was…that/who…去掉，句子仍然成立。本题强调的是主语Mr Green。句意：在我出差的时候，正是Mr Green照顾我的奶奶。故D正确。