从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
1. In the dark street, there wasn’t a single person ____ he could turn for help.
A. that B. who C. from whom D. to whom
2. ___has already been pointed out, grammar is not a set of dead rules.
A. As B. It C. That D. Which
3. What great trouble we had____ where his house was.
A.to find B. finding C. find D.found
4. In the reading room, we found her____ at a desk, with her attention____ on a book.
A. sitting fixing B. to sit fixed
C. seating fixing D. seated fixed
