2. Necessary - Not Necessary Need to - don’t need to Back office staff don’t need to wear suits or ties
3. Instructions that you think are important Must You must save your files before closing your computers down
4. Absence of obligation Don’t need to / doesn’t need to have to You don’t need / have to wear an ID badge
5. To prohibit someone from doing something Musn’t You musn’t leave the designated area
6. To say or ask if something is prohibited Be allowed to Not be allowed You aren’t allowed to bring mobile phones into the lab
7. To remind people of rules or to talk about rules that are not always observed Be supposed to / Not be supposed to You are not supposed to bring drinks in here .
8. MUST It has not past or future form. Use “have to” It is rareley used in questions
9. Need It’s possible to use Need as a modal auxiliary You needn’t go to the meeting this afternoon
