Bare infinitive

The bare infinitive is the form of the verb without "to".

The bare infinitive is used:
 * as the main verb after the auxiliary verb do, or most modal auxiliary verbs (will, can, etc.): "I will go" ( I will to go );
 * after had better: "You had better ask him";
 * with the verb help: "She helped him finish it";
 * with why: "Why do it later?".