Answer 1
You do not 'tell' him or her. You prove it by doing so.
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Answer 2
You provide examples of real-life scenarios where you have worked in a team with others and produced good results. It can be in an employment situation or not.
Some examples:
Tell the coworker it is not working and if that does not work tell him or her that u will call there partner and tell them what they are doing !!!
He was very happy.
Report it to your boss but tell the boss you want to remain anonymous.
gee i dont kno...tell them!
just tell him
You call the police.
Always be the first to apologize. If you really care about them tell them how much your relationship means to you. If you don't, just tell them you have to get along to be effective in our work and that you don't need to hold a grudge.
Try to change the subject.
if it doesnt affect you negatively
Tell someone. Tell anyone that can help. dont let it happen.
One option is the word coworker.
Your coworker could be having trouble at home, and it may be bothering her at work.