SN4 ""

No	Pattern	Freq
1	be difficult [verb] that	161
2	[be] difficult [verb] that	161
3	[is] difficult [verb] that	102
4	is difficult [verb] that	97
5	[adv] difficult [verb] that	73
6	[adv] difficult [verb] that	50
7	[pers pn] difficult [verb] that	41
8	it difficult [verb] that	41
9	[pron] difficult [verb] that	41
10	it difficult [verb] that	41
11	was difficult [verb] that	31
12	[was/were] difficult [verb] that	31
13	be difficult [verb] that	26
14	[be] difficult [verb] that	26
15	[not/n't] difficult [verb] that	23
16	not difficult [verb] that	23
17	not difficult [verb] that	21
18	more difficult [verb] that	13
19	more difficult [verb] that	13
20	very difficult [verb] that	12
21	very difficult [verb] that	12
22	so difficult [verb] that	8
23	so difficult [verb] that	8
24	's difficult [verb] that	5
25	difficult [adv] [verb] that	9
26	difficult not [verb] that	8
27	difficult [not/n't] [verb] that	8
28	difficult not [verb] that	8
29	difficult [verb] [noun] that	20
30	difficult [verb] [noun pl] that	13