They have arrived at lunch time but the flight was delayed.A. shouldB. canC. mustD. will

问题补充：

They have arrived at lunch time but the flight was delayed.

A. should

B. can

C. must

D. will

答案：

(答案→)A. should

B. can

C. must

D. will

解析：考察情态动词 should have done本应当干某事 can have done可能做了某事 must have done一定做了某事 will have done 将要做好

句意为，他们本应该在午饭的时候到达，但是航班被推迟了。