SN4 ""

No	Pattern	Freq
1	have been a major [noun]	169
2	[verb] been a major [noun]	169
3	[verb] been a major [noun sg]	168
4	[vb -s] been a major [noun]	105
5	has been a major [noun]	103
6	had been a major [noun]	28
7	[vb past] been a major [noun]	28
8	[verb] been a major factor	23
9	[verb] been a major factor	23
10	[vb infin] been a major [noun]	15
11	have been a major [noun]	15
12	have been a major [noun]	10
13	[to-vb] been a major [noun]	10
14	to have been a major [noun]	10
15	[vb base] been a major [noun]	10
16	[verb] been a major source	7
17	[verb] been a major source	7
18	[verb] been a major problem	5
19	[verb] been a major change	5
20	[verb] been a major cause	5
21	[verb] been a major change	5
22	[verb] been a major problem	5
23	[verb] been a major cause	5