Incorrect: He is taking his food.
Correct: He is having his food.

‘Taking his food‘ is not wrong, but native English speakers rarely use this expression.

Incorrect: I take your leave.
Correct: I must say goodbye.

‘I take your leave’ is not wrong, but it is extremely formal.

Incorrect: He knows to swim.
Correct: He knows how to swim.

Incorrect: Do you know to cook?
Correct: Do you know how to cook?

Know cannot be followed directly by an infinitive. We use the structure ‘know how to’.

Incorrect: Students should not cut jokes in class.
Correct: Students should not make jokes in class.

Incorrect: He cut his pencil.
Correct: He sharpened his pencil.

Incorrect: Should I cut this word?
Correct: Should I erase this word?
Correct: Should I scratch out this word?

Incorrect: The prisoner’s head was cut.
Correct: The prisoner’s head was cut off.

When the cutting divides what is cut into pieces, use cut off, cut up and cut into.

Incorrect: My back is paining.
Correct: I have a pain in my back.
Correct: My back is hurting.
Incorrect: My tooth is paining.
Correct: My tooth is aching.

Pain is a transitive verb. It must have an expressed object. When there is no object, use other words like ache or hurt.