Rewrite the following sentences using appropriate modal verbs. You may take clues from the highlighted words.
It is unnecessary to worry about things beyond your control.
You need not worry about things beyond your control. (OR: You don't need to worry about things beyond your control.)
It is not possible for a person to gain experience without taking risks.
A person cannot gain experience without taking risks.
It is essential to treat others with kindness, even when they disagree with you.
You must treat others with kindness, even when they disagree with you.
It is not allowed to interrupt when someone else is speaking.
You must not interrupt when someone else is speaking.
Explanation
(2) 'Need not' or 'don't need to' expresses that something is unnecessary. (3) 'Cannot' expresses impossibility or inability. (4) 'Must' expresses necessity or something that is essential. (5) 'Must not' expresses prohibition or something that is not allowed.