SN4 ""

No	Pattern	Freq
1	[noun] [vb past] at a time	32
2	[noun sg] [vb past] at a time	18
3	[pron] [vb past] at a time	16
4	[pers pn] [vb past] at a time	14
5	[noun pl] [vb past] at a time	8
6	[adj] [vb past] at a time	8
7	this [vb past] at a time	7
8	[det] [vb past] at a time	7
9	this [vb past] at a time	7
10	[noun prp] [vb past] at a time	6
11	it [vb past] at a time	6
12	it [vb past] at a time	6
13	they [vb past] at a time	5
14	they [vb past] at a time	5
15	[vb past] [noun] at a time	14
16	[vb past] [noun sg] at a time	13
17	[vb past] place at a time	11
18	[vb past] place at a time	11
19	[vb past] [pron] at a time	6
20	[vb past] [verb] at a time	6
21	[vb past] one at a time	6
22	[vb past] [adv] at a time	6
23	[vb past] one at a time	6
24	[vb past] [indef pn] at a time	6
25	[vb past] [vb pp] at a time	5
26	[vb past] at a [adj] time	9
27	[vb past] at a [adj] time	9
28	[vb past] at a time [Wh adv]	49
29	[vb past] at a time when	49
30	[vb past] at a time when	49