"In situations like these, we will often feel like running away or punching our enemy on the nose." Does sentence a refer to the future or to no specific time? "The same stress hormones make us aggressive or over-vigilant, and tend to cause us to overreact." Does sentence b talk about something that is always true or often true?
"Your teacher is always picking on you." Does sentence c refer to an action happening at the moment of speaking or to no specific time at all?