Practice: Must and Have To

'Must' is used to show a personal decision or conviction. In Spanish, we would use 'debo'.

'Mustn't' is used to express prohibition or something forbidden. In Spanish, we would use 'no debes'.

'Have to' is used to express an external obligation or rule. In Spanish, we would use 'tenemos que'.

'Don't have to' is used to express something optional or not obligatory. In Spanish, we would use 'no tienes que'.

If the obligation comes from an external rule or necessity, 'have to' is more appropriate. In Spanish, we would use 'tengo que'.

If the obligation is a personal decision or conviction, 'must' is more appropriate. In Spanish, we would use 'debo'.

If there's no obligation to do something, 'don't have to' is more appropriate. In Spanish, we would use 'no tienes que'.

If something is forbidden, 'mustn't' is more appropriate. In Spanish, we would use 'no debes'.

When using 'must', we don't use 'to' after it. This is a common mistake for Spanish speakers because in Spanish we do use 'deber + infinitive' (debo estudiar).

'Mustn't' is the correct form to express prohibition. The sentence 'You have not to smoke here' is a literal translation from Spanish 'no tienes que fumar aquí' and it's incorrect in English.

'Don't have to' is the correct way to express lack of obligation. The sentence 'I don't must work tomorrow' is a literal translation from Spanish 'no debo trabajar mañana' and it's incorrect in English.

After 'must', we use the base form of the verb without -s. This is a common mistake for Spanish speakers because in Spanish we do use 'debe + infinitive' (debe usar).