SN4 ""

No	Pattern	Freq
1	[be] a [adv] difficult	191
2	be a [adv] difficult	191
3	[is] a [adv] difficult	114
4	[prep] a [adv] difficult	73
5	[prep] a [adv] difficult	73
6	is a [adv] difficult	71
7	[verb] a [adv] difficult	71
8	's a [adv] difficult	43
9	[adv] a [adv] difficult	33
10	in a [adv] difficult	33
11	in a [adv] difficult	33
12	be a [adv] difficult	32
13	[be] a [adv] difficult	32
14	have a [adv] difficult	31
15	[was/were] a [adv] difficult	30
16	was a [adv] difficult	28
17	[adv] a [adv] difficult	20
18	[vb past] a [adv] difficult	18
19	[vb -s] a [adv] difficult	15
20	been a [adv] difficult	14
21	[been] a [adv] difficult	14
22	had a [adv] difficult	11
23	[vb base] a [adv] difficult	11
24	[conj] a [adv] difficult	11
25	[noun] a [adv] difficult	11
26	[pron] a [adv] difficult	10
27	[not/n't] a [adv] difficult	10
28	not a [adv] difficult	10
29	[vb pp] a [adv] difficult	9
30	[v-ing] a [adv] difficult	9