SN4 ""

No	Pattern	Freq
1	[conj] it have been [adj] for	25
2	[noun] it have been [adj] for	12
3	[subord] it have been [adj] for	12
4	[coord] it have been [adj] for	10
5	[noun sg] it have been [adj] for	8
6	[adv] it have been [adj] for	7
7	[num] it have been [adj] for	7
8	[adj] it have been [adj] for	7
9	if it have been [adj] for	6
10	if it have been [adj] for	6
11	and it have been [adj] for	5
12	[verb] it have been [adj] for	5
13	but it have been [adj] for	5
14	but it have been [adj] for	5
15	and it have been [adj] for	5
16	it [modal v] have been [adj] for	117
17	it [vb mod] have been [adj] for	117
18	it would have been [adj] for	79
19	it would have been [adj] for	79
20	it must have been [adj] for	24
21	it must have been [adj] for	24
22	it might have been [adj] for	8
23	it might have been [adj] for	8
24	it have [adv] been [adj] for	37
25	it have [adv] been [adj] for	20
26	it have not been [adj] for	17
27	it have [not/n't] been [adj] for	17
28	it have not been [adj] for	11
29	it have n't been [adj] for	6
30	it have always been [adj] for	5