The infinitive can be used with or without the marker to. These two forms of the infinitive are distinguished by the terms ‘to-infinitives’ and ‘bare infinitives’.
Uses of the bare infinitive
The infinitive without the marker to (bare-infinitive) is used after the auxiliaries shall, should, will, would, may, might, do, did, can, could, must, need and dare.
- I shall invite them.
- We must go now.
- He can speak English.
- You need not go.
- He dare not refuse.
When dare and need are used as principal verbs, they are followed by the to-infinitive.
- Did he dare to do that?
- We will need two weeks to complete the work.
The infinitive is used without to after some principal verbs like bid, watch, see, let, make, help and hear.
- I bade him come. (NOT I bade him to come.)
- Let him go. (NOT Let him to go.)
- We heard her sing. (NOT We heard her to sing.)
- I watched them play. (NOT I watched them to play.)
After rather, better and had better
The infinitive is used without to after rather, better and had better.
- You had rather visit him.
- I would rather wait.
- You had better consult a doctor.
After some prepositions like except, but, save and than
- She can do everything but cook.
- She did nothing except cry.