问题
选择题
In the dark street there wasn’t a single person _____ Mary could turn for help.
A．to whom
B．to which
C．on whom
D．on which
答案
答案：A
考察定语从句，该句为定语从句， 先行词是single person, 在从句中作turn to的宾语，turn to sb for help意为向某人求助，to 是介词，后面指人的时候只能选择whom，所以选择A