SN4 ""

No	Pattern	Freq
1	[pron] have once been	241
2	[pers pn] have once been	97
3	[Wh det] have once been	95
4	[noun] have once been	71
5	[conj] have once been	56
6	what have once been	55
7	what have once been	55
8	[that] have once been	49
9	that have once been	49
10	that have once been	49
11	[noun sg] have once been	43
12	which have once been	40
13	which have once been	40
14	who have once been	38
15	[Wh pn] have once been	38
16	who have once been	38
17	it have once been	34
18	it have once been	34
19	he have once been	28
20	he have once been	28
21	she have once been	23
22	she have once been	23
23	[noun pl] have once been	14
24	[noun prp] have once been	12
25	they have once been	11
26	there have once been	9
27	there have once been	9
28	they have once been	9
29	[ex0] have once been	9
30	have [adv] once been	17