下图这部著作的作者是
A.华佗
B.郦道元
C.张仲景
D.司马迁
答案:B
I _____ an exchange student here for a year now. [ ]
A. am
B. was
C. have been
D. had been
在日常生产中,以下哪条电路是交换信令电路正确的电路代号()。
A.北京广州30N0001NP
B.上海广州30N0001NP
C.北京上海30N2003NM
D.北京长春30N0003CLB