下图反映了欧洲中世纪的什么制度？
A．世袭制
B．封建等级制度
C．宗法制
D．军事奴隶制
答案：B
(江苏省南通市2009期末调研)Miss Li ______ as a secretary for five years in the company, and now she is general manager
of it.
A．serves
B．served
C．had served
D．has served
根据误差性质和特点，可以把测量误差分为（）、系统误差和随机误差三大类。
A、较大误差
B、较小误差
C、粗大误差
