|The usual form of infinitive is "to" + base verb. However, in certain cases, we can leave out "to." Here's how:|
|1. Infinitives after modal auxiliary verbs|
In cases where modal verbs (will, shall, would, should, can, could, might, and must) are used, infinitive can stand without "to."
I should buy some milk.
She might agree to go with us.
Can you close the door, please?
|Also, when "had better" is used, there's no need to put "to." However, when "need" and "dare" are present, "to" is omitted in negative sentences.|
They'd better correct the bill.
I needn't buy her anything.
I daren't question her ideas.
|2. Infinitives after let, make, hear, etc.|
When verbs like let, make, see, hear, feel, watch, and notice are used, the format of the sentence is: object + infinitive without to.
I didn't hear the alarm go off.
I watch them practice baseball.
She let her cats sleep in the room.
|3. Infinitives after why (not)|
The format why (not) + infinitive without to can also apply when stating a question or suggestion.
Why travel abroad?
Why do the laundry today?
Why not open the window?
|4. Infinitives after and, or, except, but, than, as, and like|
When and, or, except, but, than, as, and like are used to connect infinitives, the second infinitive can do without "to."
It's easier to spend than save money.
Would you like to drive or take the train?
On weekends, I just like to stay home and watch TV.
|Also, when using "rather than," infinitive is used without "to."|
I decided to call the agency rather than email them.
|5. Infinitive after do|
Infinitive without to also applies with the following expressions: All I did was, What I do is, etc.
All I did was (to) guide him the way.
What an airbag does is (protect) the driver during impact.