SN4 ""

No	Pattern	Freq
1	[conj] it [is] difficult	564
2	[coord] it [is] difficult	260
3	[subord] it [is] difficult	164
4	[noun] it [is] difficult	151
5	that it [is] difficult	140
6	that it [is] difficult	140
7	[that] it [is] difficult	140
8	and it [is] difficult	137
9	and it [is] difficult	137
10	but it [is] difficult	123
11	but it [is] difficult	123
12	[adv] it [is] difficult	108
13	[noun sg] it [is] difficult	103
14	[adv] it [is] difficult	88
15	[verb] it [is] difficult	69
16	[vb base] it [is] difficult	44
17	[noun pl] it [is] difficult	39
18	although it [is] difficult	36
19	although it [is] difficult	36
20	[pron] it [is] difficult	33
21	[adj] it [is] difficult	33
22	[Wh det] it [is] difficult	28
23	which it [is] difficult	27
24	which it [is] difficult	27
25	as it [is] difficult	22
26	because it [is] difficult	22
27	know it [is] difficult	22
28	as it [is] difficult	22
29	because it [is] difficult	22
30	know it [is] difficult	20