SN4 ""

No	Pattern	Freq
1	it be [adv] difficult [verb]	1078
2	it be [adv] difficult [to-vb]	1069
3	it be [adv] difficult [verb]	875
4	it is [adv] difficult [verb]	705
5	it be very difficult [verb]	319
6	it be very difficult [verb]	319
7	it 's [adv] difficult [verb]	214
8	it be [not/n't] difficult [verb]	203
9	it be not difficult [verb]	203
10	it be not difficult [verb]	185
11	it was [adv] difficult [verb]	158
12	it be extremely difficult [verb]	82
13	it be extremely difficult [verb]	82
14	it be [adv] difficult to see	80
15	it be [adv] difficult see	80
16	it be often difficult [verb]	72
17	it be often difficult [verb]	72
18	it be more difficult [verb]	70
19	it be more difficult [verb]	70
20	it be [adv] difficult get	60
21	it be [adv] difficult find	58
22	it be [adv] difficult to find	58
23	it be [adv] difficult to get	57
24	it be [adv] difficult to make	32
25	it be [adv] difficult make	32
26	it be so difficult [verb]	31
27	it be so difficult [verb]	31
28	it be sometimes difficult [verb]	30
29	it be sometimes difficult [verb]	30
30	it be [adv] difficult to imagine	28