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. Although it seemed to be ______painful experience, he still found it ______ fun.
A. a, / B. /, a C. a, the D. a, a
2. The way ______ was thought of by him ______ the experiment was similar to the way ______ you carried it out.
A. that, doing, which B. which, of doing, in which
C. what, to do, \ D. it, of doing, that
