You use thereby to introduce an important result or consequence of the event or action you have just mentioned.
Our bodies can sweat, thereby losing heat by evaporation.
我们的身体会流汗,由此能通过蒸发散热。
A firm might sometimes sell at a loss to drive a competitor out of business, and thereby increase its market power.
有些公司有时会通过亏本销售来挤垮对手,从而提升其市场地位。