(·全国卷Ⅰ)They have arrived at lunchtime but their flight was delayed.A. willB. canC. mus

问题补充：

(·全国卷Ⅰ)They have arrived at lunchtime but their flight was delayed.

A. will

B. can

C. must

D. should

答案：

A. will

B. can

C. must

(答案→)D. should

解析： 选D考查情态动词。 句意： 他们本应该在午饭时间到达，但是他们的航班推迟了。 should have done表示“本应该做某事(实际却未做)”，符合句意。