他弯下腰，解开鞋带，脱下鞋子。

He bent down, ___unfastening his shoelaces to take off his shoes.

她解开鞋带准备换鞋。

She is ___unfastening her shoelaces to change shoes.

她解开外套的扣子，准备休息。

She began ___unfastening her coat buttons, ready to relax.