The American economy is still in trouble the Chinese economy is beginning to pick up.A. w

问题补充：

The American economy is still in trouble， the Chinese economy is beginning to pick up.

A. when

B. however

C. while

D. therefore

答案：

A. when

B. however

(答案→)C. while

D. therefore

解析：这两个分句之间是明显的转折关系，表示对比，所以选C 。