温病学从伤寒体系中摆脱出来的时代为
A．唐代
B．宋代
C．元代
D．明代
E．清代
参考答案：C
—Cathy, did you attend the lecture given by Mr Black last night?
—No. I ______ a report at the office.
A．was writing
B．wrote
C．had written
D．have been writing
凹版印刷的特点是什么？
