—____ 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