问题补充：
When he was awake, she found she was lying on seemed to be a piece of stone.
A. that
B. which
C. what
D. it
答案：
A. that
B. which
(答案→)C. what
D. it
解析：考查连词。根据 seemed to be a piece of stone 缺主语可知要用what连接从句作was lying on的宾语，what相当于sth that。句意：她醒来时发现自己躺在似乎是石头的东西上面。
