Question

.......... is used to express obligation​

Answer 1

Explanation:

Have to' and 'must' are both used to express obligation. There is a slight difference in the way that they are both used. 'Have to' shows that the obligation comes from someone else, not the speaker. This is usually referring to a rule or law.

Answer 2

Have to' and 'must' are both used to express obligation. There is a slight difference in the way that they are both used. 'Have to' shows that the obligation comes from someone else, not the speaker. This is usually referring to a rule or law