Rule-1
जब Infinitive का प्रयोग Verb के बाद Objective की भांति होता है, तब Infinitive के पहले how का प्रयोग होता है (how + Infinitive)

ये Verbs है – decide, discover, ask, inquire, forget, see, learn, know, remember, think, teach, wonder, show, explain.

I know how to drive a car.
You know how to play the Guitar.

Rule-2
कुछ Verb/Adjective ऐसे है, जिसके साथ to+V1 का ही प्रयोग करते है Gerund (V4) का नहीं make, bid, behold, dare, hope, agree, decide, desire, want, wish, happy, glad, ready, fail etc.

I hope to see him.
I am ready to start.

Rule-3
Had better, had sooner, had rather, would rather, would sooner, would better के बाद बल V1 ही आएगा इन सभी शब्दों के बाद to+V1 या फिर V2/V3/V4 आदि का प्रयोग करके गलती दी जाती है |

Incorrect – I made him to run.
Correct – I made him run.
Incorrect – You had better to consulted the doctor.
Correct -You had better consulted the doctor.

Note – यदि see, watch, behold, make, bid, here का प्रयोग Passive में किया गया हो तो उसके बाद to का प्रयोग किया जाएगा |