But for your timely warning we have been unaware of the danger. Thank you very much! A. s

问题补充：

But for your timely warning, we have been unaware of the danger. Thank you very much!

A. shall

B. must

C. will

D. would

答案：

A. shall

B. must

C. will

(答案→)D. would

解析：句意：要不是你及时提醒，我们就不会意识到危险。非常感谢您！此处but for意为：要不是。

表示与过去的事实相反，主句用would+have done的形式。故选D。