SN4 ""

No	Pattern	Freq
1	[verb] to do is [prep]	30
2	[vb base] to do is [prep]	17
3	[noun] to do is [prep]	12
4	[noun sg] to do is [prep]	11
5	thing to do is [prep]	10
6	thing to do is [prep]	10
7	have to do is [prep]	8
8	have to do is [prep]	8
9	[pers pn] to do is [prep]	7
10	[pron] to do is [prep]	7
11	trying to do is [prep]	6
12	try to do is [prep]	6
13	need to do is [prep]	6
14	[v-ing] to do is [prep]	6
15	need to do is [prep]	5
16	to do [det] is [prep]	24
17	to do [adj] is [prep]	24
18	to do this is [prep]	14
19	to do this is [prep]	14
20	to do that is [prep]	10
21	to do that is [prep]	10
22	to do [adv] is [prep]	7
23	to do [adv] is [prep]	7
24	to do [pers pn] is [prep]	5
25	to do [pron] is [prep]	5
26	to do it is [prep]	5
27	to do it is [prep]	5
28	to do is [verb] [prep]	132
29	to do is [vb infin] [prep]	84
30	to do is [to-vb] [prep]	43