SN4 ""

No	Pattern	Freq
1	be difficult [to-vb]	3945
2	[is] difficult [to-vb]	2237
3	is difficult [to-vb]	1938
4	[be] difficult [to-vb]	730
5	be difficult [to-vb]	730
6	[was/were] difficult [to-vb]	525
7	was difficult [to-vb]	460
8	[am/are] difficult [to-vb]	344
9	are difficult [to-vb]	333
10	's difficult [to-vb]	299
11	[be] difficult to see	246
12	[be] difficult to find	133
13	[be] difficult to imagine	114
14	[be] difficult to know	107
15	[be] difficult to get	104
16	[be] difficult to say	97
17	been difficult [to-vb]	94
18	[been] difficult [to-vb]	94
19	[be] difficult to believe	89
20	[be] difficult to assess	80
21	[be] difficult to understand	66
22	were difficult [to-vb]	65
23	[be] difficult to tell	64
24	[be] difficult to determine	59
25	[be] difficult to obtain	58
26	[be] difficult to achieve	54
27	[be] difficult to distinguish	51
28	[be] difficult to avoid	51
29	[be] difficult to make	50
30	[be] difficult to explain	49