SN4 ""

No	Pattern	Freq
1	it is difficult [verb] for	13
2	it is difficult [to-vb] for	13
3	it is difficult account for	6
4	it is difficult to account for	6
5	[conj] it is difficult for	44
6	[that] it is difficult for	16
7	that it is difficult for	16
8	that it is difficult for	16
9	[coord] it is difficult for	15
10	[subord] it is difficult for	13
11	and it is difficult for	11
12	and it is difficult for	11
13	[noun] it is difficult for	8
14	[noun sg] it is difficult for	7
15	it is [adv] difficult for	78
16	it is [adv] difficult for	75
17	it is very difficult for	23
18	it is very difficult for	23
19	it is more difficult for	10
20	it is more difficult for	10
21	it is extremely difficult for	9
22	it is extremely difficult for	9
23	it is difficult for [pron]	57
24	it is difficult for [pers pn]	49
25	it is difficult for [art]	31
26	it is difficult for [art]	31
27	it is difficult for [noun]	28
28	it is difficult for [adj]	21
29	it is difficult for [noun pl]	20
30	it is difficult for the	19