Is it only on the world market ________ we can prove the quality of our goods?

Is it only on the world market ________ we can prove the quality of our goods?

A.that

B.ever since

C.where

D.now that

答案及解析： A

解析：

句意：是不是只有在国际市场上我们才能验证产品的质量呢？考查强调句型。