SN4 ""

No	Pattern	Freq
1	[noun] is when	11
2	[noun sg] is when	9
3	[pron] is when	9
4	[pers pn] is when	6
5	it is when	5
6	it is when	5
7	is [verb] when	502
8	is [adj] when	486
9	is [vb pp] when	455
10	is [adj] when	424
11	is [conj] when	197
12	is that when	188
13	is [that] when	188
14	is that when	188
15	is [adv] when	78
16	is [adv] when	69
17	is [v-ing] when	42
18	is use when	35
19	is used when	35
20	is important when	34
21	is important when	34
22	is [pron] when	30
23	is only when	28
24	is only when	28
25	is [adj -er] when	26
26	is [noun] when	26
27	is [det] when	24
28	is [pers pn] when	24
29	is useful when	21
30	is useful when	21