CCTV is exactly like a window on the world ________ you will sit by it and fix your attention on wha

CCTV is exactly like a window on the world ________ you will sit by it and fix your attention on what it shows.

A.if

B.as

C.while

D.unless

答案及解析： A

if引导状语从句表示一个假设。 假如你坐下来看节目，就会了解这一点。