SN4 ""

No	Pattern	Freq
1	is [adv] difficult [to-vb]	989
2	is [adv] difficult [to-vb]	825
3	is very difficult [to-vb]	228
4	is very difficult [to-vb]	228
5	is not difficult [to-vb]	164
6	is [not/n't] difficult [to-vb]	164
7	is not difficult [to-vb]	154
8	is more difficult [to-vb]	113
9	is more difficult [to-vb]	113
10	is extremely difficult [to-vb]	91
11	is extremely difficult [to-vb]	91
12	is often difficult [to-vb]	80
13	is often difficult [to-vb]	80
14	is [adv] difficult to see	59
15	is [adv] difficult to find	43
16	is [adv] difficult to make	30
17	is notoriously difficult [to-vb]	27
18	is notoriously difficult [to-vb]	27
19	is sometimes difficult [to-vb]	26
20	is sometimes difficult [to-vb]	26
21	is [adv] difficult to understand	25
22	is [adv] difficult to assess	25
23	is [adv] difficult to imagine	22
24	is always difficult [to-vb]	22
25	is always difficult [to-vb]	22
26	is [adv] difficult to establish	21
27	is [adv] difficult to determine	21
28	is [adv] difficult to predict	21
29	is [adv] difficult to get	21
30	is quite difficult [to-vb]	20