can't tie; can't fasten
トムは靴ひもが結べない。
Tom can't tie his shoelaces.
このネクタイはきちんと結べない。
I can't tie this tie properly.
トムは靴のひもが結べない。
トムったら、自分でネクタイを結べないのよ。
Tom can't even tie his own tie.
トムは自分で靴ひもを結べない。
Tom can't tie his shoelaces by himself.