Perhaps the one you least want to get wrong!
Naturally when people told me they had been running or they were running I thought they were obviously in a hurry to get somewhere or do something.
Not the case. No, far from it!
Running here can be used that way however it is also used to mean that you have diarrhoea!
No wonder when I was telling someone how I had been running (to probably catch a child, not for exercise in case you were wondering!), they looked at me both bizarrely and sympathetically!
I was more than a little embarrassed when I found out my mistake! I now phrase what I’m saying very carefully if it involves moving fast at all!