SN4 ""

No	Pattern	Freq
1	[subord] it have [been]	1971
2	[subord] it have been	1971
3	[subord] it had [been]	1094
4	[subord] it has [been]	680
5	if it have [been]	519
6	as it have [been]	323
7	[subord] it 's [been]	182
8	than it have [been]	157
9	because it have [been]	144
10	after it have [been]	132
11	once it have [been]	112
12	though it have [been]	97
13	although it have [been]	82
14	where it have [been]	80
15	when it have [been]	76
16	since it have [been]	42
17	whether it have [been]	41
18	until it have [been]	33
19	unless it have [been]	24
20	before it have [been]	20
21	for it have [been]	16
22	[subord] it 'd [been]	15
23	so it have [been]	15
24	while it have [been]	14
25	like it have [been]	14
26	cos it have [been]	11
27	whilst it have [been]	6
28	whereas it have [been]	5