You do not use it before a conjunction such as "and" or "but".

BBC: 10 questions on grammar

You argue that CCS is unproven because no power plants use it today, yet you do not recognise the economic reasons behind this.

ECONOMIST: The benefits of CCS

"You do not respect a union flag if you use it as a weapon to attack someone, " he said.

BBC: Northern Ireland

Please do not use the USB key, and we ask that you return it to IBM at Reply Paid 120, PO Box 400, West Pennant Hills 2120.

FORBES: IBM Distributes Malware-Infected USB Sticks At Security Conference

This makes the time doubly important, and it is draining away constantly whether or not you are making good use of it, so be sure to do so!

FORBES: 1) Consider time your most precious resource.