SN4 ""

No	Pattern	Freq
1	[noun] at which [noun]	545
2	[noun sg] at which [noun]	434
3	rate at which [noun]	108
4	rate at which [noun]	101
5	[noun pl] at which [noun]	100
6	level at which [noun]	51
7	point at which [noun]	45
8	age at which [noun]	42
9	age at which [noun]	39
10	point at which [noun]	37
11	level at which [noun]	37
12	speed at which [noun]	29
13	speed at which [noun]	28
14	[verb] at which [noun]	27
15	price at which [noun]	20
16	time at which [noun]	20
17	time at which [noun]	16
18	price at which [noun]	16
19	levels at which [noun]	14
20	[adj] at which [noun]	14
21	[conj] at which [noun]	11
22	[coord] at which [noun]	10
23	stage at which [noun]	10
24	meeting at which [noun]	9
25	moment at which [noun]	9
26	and at which [noun]	8
27	points at which [noun]	8
28	[num] at which [noun]	8
29	[vb pp] at which [noun]	8
30	and at which [noun]	8