To do sth.

* It is adj. for noun/pronoun to do sth.
* important, essential, vital, necessary, pointless, unnecessary
* normal, common, usual, rare
* It is adj. + to do sth.
* difficult, nice, necessary, worthwhile, important
* to do sth. is to do sth.

* ask/consider/decide/discover/understand/wonder/think how/where/whether to do sth.

* attempt, arrangement, claim, decision, determination, failure, hope, need, plan, promise, refusal, resolution, tendency, proposal, wish to do sth.

* ability, ambition, anxiety, eagerness, inclination, patience, reluctance to do

* only, last, next, first, second noun. to ..

* A book to read
* A book to read it (wrong)

* a place to live in
* a place in which to live
* a place to live (wrong)

* to be doing
* to have done

* to affect the trajectories of ballistic missiles and induce ...
* attempt to metabolize, or render harmless, the chemical irritant ..
* a procedure that allows voters to propose and pass laws, as well as to repeal them.
* say that all one has to do with cattle is leave them alone while they feed themselves and then corral them and drive them to market

* what we'll do is (to) tell here the truth
* All he did was (to) make others work
* The bus broke down. The only thing we could do was (to) talk there
* The thing to do is (to) clear the road