_______ for your laziness，you could have finished the assignment by now.
A
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couldhavedone表示与过去事实相反，条件从句应用haddone形式，had要提前构成倒装。
After months of voyage, Columbus arrived in ______ later proved to be a new continent.
The professor asked a question, and David ________ a good answer.
I'd like to remind you that there is no_____on the part of suspects to answer questions.