—____ when has the country been open to international trade?

—1978,I suppose.

A.Since                                                           B.In

C.From                                                           D.After

— __________ when has the country been open to international trade?

— 1978, I suppose.

A. Since  B. In

C. From  D. After

.—____ when has the country been open to international trade?

  —1978, I suppose.

A. Since     B. In         C. From      D. After

-----when has the country been open to international trade?

-----1978, I suppose.

A. Since      B. In         C. From               D. After

 —____ when has the country been open to international trade?

—1978,I suppose.

A.Since                                 B.In

C.From                                  D.After

—_______when has the country been open to international trade?

— 1978,I suppose.

A. Since               B. In                 C. From                 D. After

-          when has the country been open to international trade?

- 1978, I suppose. 

A. Since                B. In                     C. From                D. After

—　 ______ when has the country been open to international trade?

—1978, I suppose.

A. Since　　　 　 　B. In　　　　　 　 C. From　　　　　 　 D. After

--________ when has the country been open to international trade?

--1978, I suppose.（2007·陜西）

[　　]