问题
选择题
They________have arrived at lunchtime but their flight was delayed.(2011·全国 )
A．will
B．can
C．must
D．should
答案
答案：D
D [考查虚拟语气的用法。句意为：他们本该午饭时到达，但他们的航班推迟了。should have done本来应该做某事，而实际没做。but their flight was delayed这样的结果，说明他们本来该到达却没有到达，因此选D。]