天平的正确性是指什么？
参考答案：天平的正确性就是指横梁的左.右两臂具有正确固定的比例而言。
I wrote ______ article on the educational visit to Canada for the school newspaper last night. [ ]
A. the
B. an
C. a
D. /
表里同病而见喘的证候有哪些？简述各自的主证、病机、治法及方药。
