SN4 ""

No	Pattern	Freq
1	have been [v-ing] for [adj] years	139
2	have been [v-ing] [prep] [num] years	103
3	has been [v-ing] [prep] [adj] years	61
4	had been [v-ing] [prep] [adj] years	45
5	have been [v-ing] [prep] [det] years	36
6	have been [v-ing] [prep] [adj] years	21
7	have been running [prep] [adj] years	18
8	have been [v-ing] [prep] several years	14
9	have been [v-ing] [prep] several years	14
10	have been [v-ing] [prep] many years	13
11	have been [v-ing] [prep] many years	13
12	've been [v-ing] [prep] [adj] years	12
13	have been [v-ing] [prep] two years	11
14	have been [v-ing] [prep] three years	11
15	have been [v-ing] [prep] two years	11
16	have been [v-ing] [prep] three years	11
17	have been going [prep] [adj] years	10
18	have been [v-ing] [prep] some years	9
19	have been [v-ing] [prep] some years	9
20	have been [v-ing] in [adj] years	8
21	have been [v-ing] [prep] twenty years	8
22	have been [v-ing] [prep] [adj] years	8
23	have been trying [prep] [adj] years	8
24	have been [v-ing] [prep] twenty years	8
25	have been [v-ing] [prep] recent years	8
26	have been [v-ing] [prep] recent years	8
27	have been working [prep] [adj] years	7
28	have been flying [prep] [adj] years	6
29	have been [v-ing] [prep] five years	6
30	have been [v-ing] [prep] five years	6