Had I known about this computer program, a huge amount of time and energy . A.would ha

正确答案：A
解析： 本题考查虚拟语气。根据句子的倒装特征判断此处是省略了if的虚拟语气，原形是：If I had known about this computer program, a huge amount of time and energy       .故选择A。句意为：如果我早知道这个电脑程序，就可以节省大量的时间和精力了。