SN4 ""

No	Pattern	Freq
1	[noun] [is] often	1982
2	[noun sg] [is] often	1667
3	[pron] [is] often	1641
4	[pers pn] [is] often	1153
5	it [is] often	1073
6	it [is] often	1073
7	[conj] [is] often	260
8	[adj] [is] often	255
9	[Wh det] [is] often	236
10	[det] [is] often	219
11	[ex0] [is] often	215
12	there [is] often	215
13	there [is] often	215
14	[noun pl] [is] often	211
15	this [is] often	175
16	this [is] often	175
17	which [is] often	166
18	which [is] often	166
19	[subord] [is] often	107
20	[coord] [is] often	93
21	[verb] [is] often	82
22	as [is] often	81
23	as [is] often	81
24	and [is] often	75
25	and [is] often	75
26	[noun prp] [is] often	72
27	what [is] often	70
28	what [is] often	70
29	that [is] often	60
30	that [is] often	60