is a very common verb, especially in informal speaking and writing
The main verb can never be the to-infinitive.
is a modal auxiliary verb
The auxiliary verb ___ is invariable
We use it for talk about obligation
We can use ___ + -ed form to describe things that happen to us, often things which are unfortunate and which we don’t want to happen
we use ___ + object (o) + -ed form, we say that we cause something to happen or to be done.
We use it for talk about probability and expectation
The past form of ___ is used in combination with ‘have’ to express possession in a similar way to ‘have’.
We use it for give advice or make recommendations