_______ for your laziness，you could have finished the assignment by now.

正确答案： A
答案分析： 句意： 要不是你懒惰， 到现在你就能完成任务了。 本题是一个省略 if 的虚拟条件句， 主句用 could have done表示与过去事实相反，条件从句应用 had done形式， had 要提前构成倒装。