SN4 ""

No	Pattern	Freq
1	[verb] been operating	92
2	have been operating	92
3	[vb -s] been operating	42
4	has been operating	42
5	have been operating	23
6	[vb base] been operating	23
7	had been operating	19
8	[vb past] been operating	19
9	[adv] been operating	7
10	[adv] been operating	7
11	have been operating	5
12	[vb infin] been operating	5
13	been operating [prep]	60
14	been operating [prep]	60
15	been operating in	20
16	been operating in	20
17	been operating for	18
18	been operating for	18
19	been operating [adv]	13
20	been operating [adv]	11
21	been operating [art]	8
22	been operating [art]	8
23	been operating since	7
24	been operating since	7
25	been operating a	7
26	been operating a	6