问题补充：
A survey was carried out on the death rate of those who were infected by SARS, were surprising.
A. as results
B. which results
C. the results of it
D. the results of which
答案：
A. as results
B. which results
C. the results of it
(答案→)D. the results of which
解析： D the results of which 等于whose results，是非限制性定语从句。
