SN4 ""

No	Pattern	Freq
1	an [noun sg] at the [noun]	343
2	an [noun sg] at the [noun sg]	265
3	an [noun sg] at the [noun prp]	65
4	an [noun sg] at the end	22
5	an [noun sg] at the end	22
6	an exhibition at the [noun]	18
7	an [noun sg] at the time	17
8	an [noun sg] at the time	17
9	an evening at the [noun]	15
10	an appearance at the [noun]	12
11	an office at the [noun]	10
12	an [noun sg] at the [noun pl]	10
13	an [noun sg] at the university	10
14	an hour at the [noun]	10
15	an [noun sg] at the university	10
16	an official at the [noun]	9
17	an appointment at the [noun]	8
18	an explosion at the [noun]	8
19	an [noun sg] at the beginning	7
20	an [noun sg] at the moment	7
21	an [noun sg] at the moment	7
22	an [noun sg] at the beginning	7
23	an [noun sg] at the bank	6
24	an incident at the [noun]	6
25	an accident at the [noun]	6
26	an [noun sg] at the bank	6
27	an [noun sg] at the theatre	5
28	an under-secretary at the [noun]	5
29	an [noun sg] at the theatre	5
30	an eyebrow at the [noun]	5