SN4 ""

No	Pattern	Freq
1	once a [noun sg]	1545
2	once [art] week	487
3	once the [noun sg]	447
4	once [art] year	259
5	once [art] month	205
6	once [art] day	81
7	once [art] fortnight	80
8	once an [noun sg]	61
9	once every [noun sg]	44
10	once [art] home	15
11	once [art] woman	10
12	once [art] member	9
13	once [art] person	9
14	once [art] quarter	9
15	once [art] man	8
16	once [art] child	8
17	once [art] term	7
18	once [art] war	7
19	once [art] case	7
20	once [art] world	7
21	once [art] hour	7
22	once [art] couple	6
23	once [art] student	6
24	once [art] centre	6
25	once [art] government	6
26	once [art] site	6
27	once [art] sun	5
28	once [art] business	5
29	once [art] soldier	5