fit is a must for

fit Verb

— When you fit something, you match a thing for size, shape or other qualities. They fitted his hat. — When a thing fits, it is a good match for something. These shoes fit me very well.

fit Adjective

— When you are fit, you are healthy and able to do a task. After he slept he looked very fit.

fit Noun

— When you have a fit, you have a sudden emotion. He hit the man in a fit of rage. — If you have a fit, your body moves very quickly without your control. The man had a fit of epilepsy. I suddenly had a coughing fit that I could not stop.

is Verb

— A form of the verb be when talking about someone or something else. He is late for class. Is it hot in here?

a Determinative

— A is used when the following word could be any of a certain type. Compare "A book I saw on the shelf" and "The book I gave you yesterday".

a Noun

— A is the first letter of the alphabet. The letter "a" comes before "b". — In some schools, an A is a very high grade. Ron got an A on his earth science test.

must Verb

— Must is usually used to tell someone they have no choice about doing something because it is important or because of a rule or law. She must get her medicine soon or she will die.

for Preposition

— shows that something belongs to something else, or has a specific function This cake is for you. This is a net for catching fish. — For is used to show the reason for something He was angry, for he had never been called such terrible names before.

for Subordinator

— For introduces a clause with a subject and a to-infinitive It's not good for you to be too relaxed.