The verb be is a very special verb in English.
I am going to do it
for two days, since 1st April
She insists that he come.
Active voice and passive voice
Cats eat mice. Mice are eaten by cats.
I used to do it. I am not used to it.
I will do it. I am going to do it. I am doing it. I do it.
if I win, if I won, if I had won
can, shall, must...
Including phrasal verbs
put out, look after, get on with
Do you like tea? Why do you like tea? Do you like tea or coffee?
You like me, don't you?
I like to do, I like doing
Am I being silly?
In general a subject and a verb must agree in number: a singular subject takes a singular verb; a plural subject takes a plural verb. But life isn't always that easy.
Verbs in -ing form sometimes act like nouns.
fishing is fun, I hate working