问题补充：
In the dark street, there wasn’t a single person she could turn for help.
A. who
B. whom
C. that
D. to whom
答案：
A. who
B. whom
C. that
(答案→)D. to whom
解析：本题考查定语从句。根据句意表示“向某人求助”是turn to sb. for help，其中介词to可提前，故答案为D。本句也可以如下表达：In the dark street, there wasn’t a single person (who/whom/that) she could turn to for help.)
