SN4 ""

No	Pattern	Freq
1	which have been [v-ing] [prep]	128
2	[Wh det] has been [v-ing] [prep]	81
3	[Wh det] had been [v-ing] [prep]	75
4	what have been [v-ing] [prep]	67
5	[Wh det] have been happening [prep]	55
6	[Wh det] have been [v-ing] in	49
7	[Wh det] have been [v-ing] for	37
8	[Wh det] 's been [v-ing] [prep]	25
9	[Wh det] have been [v-ing] on	18
10	[Wh det] have been [v-ing] to	18
11	[Wh det] have been running [prep]	14
12	[Wh det] have been [v-ing] [prep]	14
13	[Wh det] have been [v-ing] with	12
14	[Wh det] have been [v-ing] at	11
15	[Wh det] have been going [prep]	11
16	[Wh det] have been operating [prep]	9
17	[Wh det] have been [v-ing] since	9
18	[Wh det] have been working [prep]	9
19	[Wh det] have been [v-ing] from	7
20	[Wh det] have been missing [prep]	6
21	[Wh det] have been [v-ing] over	5