'Unable' in the Bible

Thus in Judah it was said,“The strength of the burden bearers is failing,Yet there is much rubbish;And we ourselves are unableTo rebuild the wall.”

So I sent messengers to them saying, "I am engaged in an important work, and I am unable to come down. Why should the work come to a halt when I leave it to come down to you?"

The following are those who came from Tel-melah, Tel-harsha, Cherub, Addon, and Immer, but were unable to prove that their families and ancestors were Israelite:

Half of their children spoke the language of Ashdod (or the language of one of the other peoples mentioned) and were unable to speak the language of Judah.