--- The fog is so thick that the express way ______ have been closed.
--- You are right. I ______ have thought of that. Now we have to take another road.A.can; shouldB.may; canC.should; mustD.must; should
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D解析考查情态动词：第一空填must表示猜测：一定是，第二空填should have done“本该做…却没做“，句意是：--这场雾很大，高速公路一定关了。--你是对的，--我本该想到的，现在只好另外走一条路了。选D。