The student was at________loss when________word came that he would be asked to come to

the office and explain his reason for being late for school. [ ]

A. a；the

B. /；/

C. the；the  

D. a；/

现代企业制度的基础是完善的（）。

A.有限责任制度 

B.收入分配制度 

C.企业法人制度 

D.社会保障制度