SN4 ""

No	Pattern	Freq
1	over a long period [prep]	93
2	over a long period [prep]	93
3	over a long period of	84
4	over a long period of	84
5	over a long period [conj]	16
6	over a long period [coord]	12
7	over a long period and	11
8	over a long period and	11
9	over a long period [vb mod]	5
10	over a long period [modal v]	5
11	over a long period [verb]	5
12	[noun] over a long period	120
13	[noun sg] over a long period	81
14	[verb] over a long period	46
15	[vb pp] over a long period	44
16	[noun pl] over a long period	34
17	[adv] over a long period	22
18	[adv] over a long period	17
19	[conj] over a long period	11
20	[coord] over a long period	8
21	[adj] over a long period	6
22	[adv prt] over a long period	5
23	over [det] a long period	5
24	over such a long period	5
25	over such a long period	5
26	over [adj] a long period	5
27	over a [adv] long period	21
28	over a [adv] long period	21
29	over a much long period	9
30	over a much long period	9