SN4 ""

No	Pattern	Freq
1	[conj] it is [adv] difficult	203
2	[coord] it is [adv] difficult	82
3	that it is [adv] difficult	66
4	that it is [adv] difficult	66
5	[that] it is [adv] difficult	66
6	[conj] it is very difficult	65
7	[subord] it is [adv] difficult	55
8	and it is [adv] difficult	47
9	and it is [adv] difficult	47
10	but it is [adv] difficult	35
11	but it is [adv] difficult	35
12	[conj] it is more difficult	25
13	[conj] it is often difficult	25
14	because it is [adv] difficult	16
15	because it is [adv] difficult	16
16	[conj] it is extremely difficult	15
17	as it is [adv] difficult	9
18	[conj] it is sometimes difficult	9
19	as it is [adv] difficult	9
20	[conj] it is so difficult	7
21	[conj] it is particularly difficult	6
22	although it is [adv] difficult	6
23	since it is [adv] difficult	6
24	since it is [adv] difficult	6
25	although it is [adv] difficult	6
26	[conj] it is notoriously difficult	5