SN4 ""

No	Pattern	Freq
1	it have [been] [v-ing]	414
2	it have been [v-ing]	414
3	it 's [been] [v-ing]	151
4	it has [been] [v-ing]	132
5	it had [been] [v-ing]	125
6	it have [been] going	60
7	it have [been] raining	27
8	it have [been] working	17
9	it have [been] running	12
10	it have [been] happening	9
11	it have [been] doing	9
12	it have [been] sitting	8
13	it have [been] lying	7
14	it have [been] developing	7
15	it have [been] standing	7
16	it have [been] coming	6
17	it have [been] playing	6
18	it have [been] building	6
19	it have [been] getting	6
20	it have [been] operating	6
21	it have [been] holding	6
22	it have [been] travelling	5
23	it have [been] making	5
24	it have [been] snowing	5
25	it have [been] selling	5
26	it have [been] hanging	5