SN4 ""

No	Pattern	Freq
1	an open [noun]	1637
2	an open [noun sg]	1598
3	an open mind	131
4	an open mind	131
5	an open letter	86
6	an open letter	86
7	an open question	66
8	an open question	66
9	an open fire	61
10	an open fire	61
11	an open door	55
12	an open door	55
13	an open system	47
14	an open window	43
15	an open window	43
16	an open day	42
17	an open day	41
18	an open invitation	37
19	an open invitation	37
20	an open air	33
21	an open space	33
22	an open air	33
23	an open space	33
24	an open verdict	29
25	an open verdict	29
26	an open [noun pl]	28
27	an open system	27
28	an open market	24
29	an open market	24
30	an open meeting	23