SN4 ""

No	Pattern	Freq
1	it is [adv] [verb] that [adj]	249
2	it is [adv] [vb pp] that [adj]	240
3	it is [adv] [verb] that [det]	141
4	it is [adv] [verb] that [adj]	94
5	it is [adv] [verb] that this	39
6	it is [adv] [verb] that this	39
7	it is generally [verb] that [adj]	36
8	it is [adv] know that [adj]	31
9	it is [adv] known that [adj]	31
10	it is well [verb] that [adj]	30
11	it is [adv] assumed that [adj]	26
12	it is [adv] assume that [adj]	26
13	it is often [verb] that [adj]	26
14	it is [adv] accept that [adj]	25
15	it is [adv] accepted that [adj]	25
16	it is widely [verb] that [adj]	23
17	it is also [verb] that [adj]	22
18	it is now [verb] that [adj]	21
19	it is sometimes [verb] that [adj]	18
20	it is [adv] [verb] that such	17
21	it is [adv] [verb] that such	17
22	it is [adv] say that [adj]	17
23	it is [adv] said that [adj]	17
24	it is [adv] [verb] that these	16
25	it is [adv] [verb] that these	16
26	it is [adv] recognise that [adj]	15
27	it is [adv] recognised that [adj]	15
28	it is [adv] [verb] that all	15
29	it is [adv] [verb] that all	15
30	it is [adv] [verb] that some	12