SN4 ""

No	Pattern	Freq
1	[pron] could have been [det] [noun]	23
2	[pers pn] could have been [det] [noun]	11
3	there could have been [det] [noun]	10
4	there could have been [det] [noun]	10
5	[ex0] could have been [det] [noun]	10
6	it could have been [det] [noun]	7
7	it could have been [det] [noun]	7
8	could [adv] have been [det] [noun]	8
9	could [not/n't] have been [det] [noun]	6
10	could not have been [det] [noun]	6
11	could have been [prep] [det] [noun]	11
12	could have been [prep] [det] [noun]	11
13	could have been [vb pp] [det] [noun]	7
14	could have been in [det] [noun]	7
15	could have been in [det] [noun]	7
16	could have been [verb] [det] [noun]	7
17	could have been [det] [adj] [noun]	6
18	could have been [det] [adj] [noun]	5
19	could have been [det] [noun] [prep]	12
20	could have been [det] [noun] [prep]	12