Question

英语题目第五大题！

Answer 1

1. must表示主观，必须。  
   We must help each other.  
   My sister is ill, my mother has to look after her.  

2. have to表示客观，必须，不得不。My sister is ill, my mother has to look after her.  

3. mustn't表示,"一定不行",you mustn't run againt the traffic light.

4. 而don't have to 表示不需要.  you don't have to finish it in such a short time.你并不需要在那么短的时间内完成它!