It’s not so easy to know when and why you need to use the bare infinitive (run, joke, make etc.), a gerund or ‘to’ + infinitive, and whether or not it is correct. There are three rules as to why we use the bare infinitive (infinitive without ‘to’ or -ing):
The bare infinitive is used after modal auxiliary verbs (helping verbs; Can & Could, may & might, will & shall, must, would, ought to & should, need to, dare to)
We use the bare infinitive after many verbs or perception, verbs used to perceive. (see, notice, hear etc.)
We use the bare infinitive with ‘why’ Interrogatives; wh-? words and how? (why leave/help/find etc). ,
(1) we use the bare infinitive after modal auxiliaries, but not after need to, dare to and ought to, due to their nature (these modal auxiliaries are connected to ‘to’):
|Can||I can tell you where he is if you like.|
|Could||They could know.|
|May||She may head out to the party tonight.|
|Might||Sophie might understand it better.|
|Will||Will you please be quiet?|
|Shall||They shall know by tomorrow.|
|Must||Harry, you must not cross a red light!|
|Would||Would you be able to help me?|
|Should||George should definitely run the marathon.|
|Ought to||* You ought to know what he said.|
|Need to||*Sir. please, you need to listen to him.|
|Dare to||*They dared me to jump off.|
(2) We use the bare infinitive after many verbs of perception, verbs used to perceive. (Can also take the gerund form):
|Watch||I watched you leave/leaving yesterday.|
|See||I didn’t see you work/working.|
|Hear||Harry can hear me speak/speaking.|
|Notice||I notice you quarrel a fair bit.|
|Feel||I felt you check/checking my ears.|
|Sense||I sensed them come/coming.|
|Smell||The dog can smell you eat/eating.|
(3) We use the bare infinitive with ‘why’:
Why did you leave so early last night?
Why go now?
Why not learn to sail?
Why write when you can type?
Why have I not seen you before?