Professor Smith, along with his assistants,          on the project day and night to meet the deadline

(截止日期).   [ ]

A. work            

B. working        

C. is working        

D. were keeping

在评价国际投资环境时，投资者一般考虑的因素包括（）

A.获利性

B.安全性

C.利润可汇性

D.合作期限

E.货币稳定性