Warnings.

• Warnings are used to ensure safety, to prevent damage to equipment and breaches of security and to ensure the law is not broken. The simplest warnings are basic instructions NOT to do something: Don't do X / No + -ing / Avoid +-ing / Never do X
• Sometimes the warning is twinned with matching good practice: Always do X, never do Y / Do X rather than Y
• Warnings may be made stronger by using must/mustn't and in some cases should/shouldn't. (Do this exercise to see the difference)
• If there's any reason to fear the warning may not be understood, a reason for the warning may be added: Never use a screwdriver to extract ICs, the pins are very fragile
• EXERCISE: Rewrite each of these warnings and give a reason where appropriate:
  
  - Don't give open access to PCs (avoid)
  Avoid giving open access to PC because you can be hacked/ you may get viruses.
  - You must not use your own programs on these machines (never)
  Never use your own programs because you may introduce viruses.
  - No coffee in this lab (must not)
  You must not drink coffee in this lab because the keyboards can get wet/be damaged.
  - Avoid giving financial information in a chat room (don't)
  Don’t give financial information in a chat room because you can be cheated/phished.
  - Never give out your password (always)
  Always protect your password because it is important for your private life
  - Don't use out-of-date antivirus software (use)
  Use up to date antivirus software to protect your PC
  - Never use a computer that has been standing for a long time in a cold environment without waiting until it has reached normal room temperature (always)
  Always wait until your computer has reached normal room temperature before using it or you may damage the hard disk.
  - Cards must not be removed from their anti-static packing until required (never)
  Never remove cards from their anti static packing because you can damage them.
  - Use an IC extraction tool, don't use a screwdriver (rather than)
  Use an IC extraction tool rather than a screwdriver.
  - Always ensure the power is switched off when working on a computer (must not)
  You must not work on a power-connected computer because you can get shocked/electrocuted.
• You can find an interesting explanation on modals and do some exercises HERE.
• Download Modal Verbs worksheet HERE.