SN4 ""

No	Pattern	Freq
1	[verb] become a	1493
2	have become a	1492
3	[vb -s] become a	729
4	has become a	720
5	had become a	552
6	[vb past] become a	552
7	[vb base] become a	119
8	have become a	108
9	[vb infin] become a	48
10	have become a	47
11	be become a	32
12	[be] become a	32
13	[is] become a	31
14	's become a	28
15	[to-vb] become a	27
16	to have become a	27
17	[not/n't] become a	26
18	not become a	26
19	[adv] become a	26
20	not become a	20
21	[v-ing] become a	15
22	having become a	15
23	've become a	11
24	's become a	9
25	n't become a	6
26	become [adv] a	36
27	become [adv] a	36
28	become [prep] a	20
29	become [prep] a	20
30	become [adj] a	20