What is infinitive form of verb? - It is of the form to + simple form of verb.e.g - to take ; to surprise.
Uses of the Infinitive -
1). After a verb - Verbs such as want, promise, plan, manage, forget, choose, prove, hope, pretend, need, expect, decide are followed immediately by an infinitive.
They expect to win the game.
She needs to apply for a scholarship.
2). After verb and object - With verbs that take an object, such as force, allow, believe, need, persuade, urge, expect, want, the infinitive follows the object.
She persuaded us to wait.
She urged her supporters not to leave.
3). After certain adjectives and nouns - Adjectives such as anxious, sorry, easy, difficult, right, wrong, can be followed by infinitives.
It is easy (for you) to get to my house.
He was eager to meet his new boss.
Some nouns (such as way, place, time, decision, job, aim) are frequently followed by an infinitive.
He has no place to relax.
It is time to go.
4). To express purpose
He is working at night (in order) to earn more money.
The Infinitive Without to
The infinitive form without to is used in the following idiomatic expressions.
1). After a causative make, let , have + object
He made his sister drive the whole way.
He had her pay for the gas, too.
2). After the verb help
They helped us solve the problem.