The program is like a window on the world you sit by it and fix your attention on what it

问题补充：

The program is like a window on the world you sit by it and fix your attention on what it shows.

A. if

B. as

C. while

D. unless

答案：

1(答案→)A. if1B. as1C. while1D. unless1解析：本题主要考查对句子间逻辑关系的理解。选项A表示条件；选项B表示时间或原因；选项C表示时间；选项D表示否定意义的条件。根据句子的逻辑关系，答案为A。