SN4 ""

No	Pattern	Freq
1	it is difficult [to-vb]	1523
2	it is difficult to see	185
3	it is difficult see	185
4	it is difficult to imagine	78
5	it is difficult imagine	78
6	it is difficult know	63
7	it is difficult to know	62
8	it is difficult believe	55
9	it is difficult to believe	55
10	it is difficult say	45
11	it is difficult to say	45
12	it is difficult assess	40
13	it is difficult to find	40
14	it is difficult to assess	40
15	it is difficult find	40
16	it is difficult to avoid	31
17	it is difficult avoid	31
18	it is difficult to understand	30
19	it is difficult understand	30
20	it is difficult get	25
21	it is difficult to get	25
22	it is difficult think	22
23	it is difficult to think	22
24	it is difficult to determine	21
25	it is difficult determine	21
26	it is difficult to distinguish	20
27	it is difficult distinguish	20
28	it is difficult to make	19
29	it is difficult make	19
30	it is difficult to tell	17