单选题 Thomas Edison, ______ seemed to be awkward in his childhood.
A. a great inventor B. was a great inventor C. a great inventor who D. who, as a great inventor

【正确答案】 A
【答案解析】伟大的发明家托马斯·爱迪生在孩童时期似乎很笨。考查主语同位语。本句已有的部分结构很完整，可见空白处为插入语，可以填入定语、状语或同位语，结合选项只有A符合题意，作此处作主语的同位语。