SN4 ""

No	Pattern	Freq
31	it is [adv] possible for	99
32	it is [adv] possible for	99
33	it is [adv] [vb pp] for	98
34	it is [adv] important for	77
35	it is [adv] important for	77
36	it is [adv] difficult for	75
37	it is [adv] difficult for	75
38	it is [adv] easy for	53
39	it is [adv] common for	40
40	it is [adv] common for	40
41	it is [adv] [adj -er] for	38
42	it is [adv] easy for	35
43	it is [adv] impossible for	34
44	it is [adv] impossible for	34
45	it is [adv] [adv] for	29
46	it is [adv] rare for	29
47	it is [adv] rare for	28
48	it is [adv] use for	27
49	it is [adv] used for	27
50	it is [adv] [v-ing] for	27
51	it is [adv] necessary for	26
52	it is [adv] necessary for	26
53	it is [adv] [adv] for	23
54	it is [adv] good for	23
55	it is [adv] useful for	19
56	it is [adv] useful for	19
57	it is [adv] essential for	18
58	it is [adv] easier for	18
59	it is [adv] essential for	18
60	it is [adv] hard for	16