SN4 ""

No	Pattern	Freq
1	could have been [verb]	1134
2	could have been [vb pp]	1056
3	could have been [v-ing]	93
4	could have been avoid	52
5	could have been avoided	52
6	could have been use	50
7	could have been do	48
8	could have been used	48
9	could have been done	43
10	could have been make	38
11	could have been made	37
12	could have been put	22
13	could have been kill	21
14	could have been killed	21
15	could have been put	20
16	could 've been [verb]	19
17	could have been take	18
18	could have been achieved	17
19	could have been prevent	17
20	could have been prevented	17
21	could have been taken	17
22	could have been achieve	17
23	could have been cause	15
24	could have been forgive	15
25	could have been caused	15
26	could have been forgiven	15
27	could have been write	14
28	could have been saved	13
29	could have been save	13
30	could have been expect	12