Question

1 A best friend should / doesn't have to always be honest and tell the truth. 2 John doesn't have to / mustn't do any homework tonight. He did it all last night. 3 You don't have to / mustn't talk in the library. You have to / shouldn't study quietly. 4 I have to / don't have to phone Jack. I talked to him at school today. 5 You have to/ don't have to keep Monica's secret. She would be unhappy if you told anyone.​

Answer 1

A best friend should always be honest and tell the truth.
John doesn't have to do any homework tonight. He did it all last night.
You don't have to talk in the library. You have to study quietly.
I don't have to phone Jack. I talked to him at school today.
You have to keep Monica's secret. She would be unhappy if you told anyone.

Answer 2

Let's break down each sentence to determine the correct choice between "have to," "don't have to," "mustn't," and "should/shouldn't":

1. "A best friend should / doesn't have to always be honest and tell the truth." - "Should" implies an expectation or recommendation, while "doesn't have to" suggests it's not a requirement. It depends on the perspective. If you're emphasizing the importance of honesty, "should" fits better. If you're acknowledging that honesty isn't always mandatory, then "doesn't have to" is more suitable.

2. "John doesn't have to / mustn't do any homework tonight. He did it all last night." - "Doesn't have to" indicates it's not necessary, while "mustn't" implies a prohibition. Since John completed his homework last night, the correct choice is "doesn't have to." It's not required because it's already done.

3. "You don't have to / mustn't talk in the library. You have to / shouldn't study quietly." - Libraries typically expect quiet, so "mustn't" would suggest a prohibition against talking. "Shouldn't" is more appropriate for the second part as it implies a recommendation for studying quietly. Therefore, the correct choices are "mustn't" for talking in the library and "shouldn't" for studying quietly.

4. "I have to / don't have to phone Jack. I talked to him at school today." - "Don't have to" implies no obligation, and since you already spoke to Jack at school, there's no necessity to call him. So, "don't have to" is the correct choice.

5. "You have to / don't have to keep Monica's secret. She would be unhappy if you told anyone." - "Have to" suggests an obligation, while "don't have to" indicates there's no necessity. Since it's about keeping a secret to avoid making Monica unhappy, "have to" is the suitable choice.

Would you like more details or examples for any of these sentences?