(i) You are obliged to do your duty irrespective of consequences.

You must do your duty irrespective of consequences.

(ii) You will do well to study at least for an hour every day.

You should study at least for an hour every day.

(iii) The doctor says it is necessary for her to sleep eight hours every night.

The doctor says she must sleep for eight hours every night.

(iv) It is right that you show respect towards elders and affection towards youngsters.

You ought to show respect towards elders and affection towards youngsters.

(v) If you want to stay healthy, exercise regularly.

You must exercise regularly to stay healthy.

(vi) It is good for you to take a walk every morning.

You should take a walk every morning.

(vii) It is strongly advised that you don’t stand on your head.

You must not stand on your head.

(viii) As he has a cold, it is better for him to go to bed.

As he has a cold, he should go to bed.