SN4 ""

No	Pattern	Freq
1	[pers pn] [vb mod] have been [adj]	1448
2	[pers pn] [modal v] have been [adj]	1416
3	[pers pn] would have been [adj]	810
4	[pers pn] would have been [adj]	734
5	it [modal v] have been [adj]	707
6	[pers pn] must have been [adj]	247
7	[pers pn] must have been [adj]	247
8	he [modal v] have been [adj]	214
9	i [modal v] have been [adj]	160
10	[pers pn] might have been [adj]	131
11	[pers pn] might have been [adj]	131
12	she [modal v] have been [adj]	127
13	[pers pn] [modal v] have been able	113
14	they [modal v] have been [adj]	111
15	[pers pn] may have been [adj]	83
16	[pers pn] may have been [adj]	83
17	[pers pn] should have been [adj]	79
18	[pers pn] should have been [adj]	79
19	[pers pn] 'd have been [adj]	76
20	[pers pn] could have been [adj]	75
21	[pers pn] could have been [adj]	75
22	you [modal v] have been [adj]	64
23	we [modal v] have been [adj]	48
24	[pers pn] [modal v] have been difficult	48
25	[pers pn] [modal v] have been nice	45
26	[pers pn] [modal v] have been possible	37
27	[pers pn] [modal v] have been easy	35
28	[pers pn] [modal v] have been happy	32
29	[pers pn] [modal v] have been impossible	30
30	[pers pn] [modal v] have been different	25