not able to do something. In ordinary speech can’t do something is the more usual way of saying this
Some of the children were unable to read or write.
feel unable to do something: Many teenagers feel unable to talk to their parents about their problems.
quite unable to do something (=completely unable): He was quite unable to control his emotions.
unwilling or unable to do something: The security forces are either unwilling or unable to spend more money.
Synonyms and related words