Without the air to hold some of the sun’s heat, the earth at nightvery cold, too cold for

Without the air to hold some of the sun’s heat, the earth at night very cold, too cold for us to live.
A. will be
B. would have been
C. is
D. would be

A. will beB. would have beenC. is(答案→)D. would be解析：考查虚拟语气。本题考查与现在事实相反的虚拟语气，故用would + v原形。句意：:(如果)没有大气保存太阳部分的热量,地球的晚上也会刺骨的寒冷,冷得对我们来说无法居住。

谢谢解答