SN4 ""

No	Pattern	Freq
1	[be] difficult to define	44
2	be difficult to define	44
3	[adv] difficult to define	29
4	[adv] difficult to define	29
5	is difficult to define	27
6	[is] difficult to define	27
7	more difficult to define	9
8	more difficult to define	9
9	are difficult to define	8
10	[am/are] difficult to define	8
11	[be] difficult to define	6
12	be difficult to define	6
13	often difficult to define	5
14	often difficult to define	5
15	difficult [noun] to define	6
16	difficult to define [conj]	20
17	difficult to define [coord]	15
18	difficult to define and	10
19	difficult to define and	10
20	difficult to define [adv]	9
21	difficult to define [adv]	9
22	difficult to define [art]	8
23	difficult to define [art]	8
24	difficult to define [prep]	6
25	difficult to define [prep]	6
26	difficult to define [pron]	5
27	difficult to define but	5
28	difficult to define [subord]	5
29	difficult to define the	5
30	difficult to define the	5