is known to the world the Chinese in many places the old tradition.A. That; keep on B.

问题补充：

is known to the world, the Chinese in many places the old tradition.

A. That; keep on

B. which; keep out

C. It ; keep back

D. As; keep up

答案：

A. That; keep on

B. which; keep out

C. It ; keep back

(答案→)D. As; keep up

解析：第一空考查由as引导的非限制性定语从句，as 正如，指后半句话的含义，keep up 保持，句意：正如全世界所知，在许多地方中国人保持着古老的传统。所以选D。