问题补充：
Having taken our seats, .
A. the professor began the lecture
B. the lecture began in no time
C. we were attracted by the lecture immediately
D. the bell announced the beginning of the lecture
答案：
A. the professor began the lecture
B. the lecture began in no time
(答案→)C. we were attracted by the lecture immediately
D. the bell announced the beginning of the lecture
解析：句意：入座之后，我们立刻被演讲所吸引。根据Having taken our seats，这里用的主动可知，因为主句的主语与take之间是主动关系，所以主句的主语必须人，故排除BD，又根据句意故选C。
