1. be unable to do sth = be powerless to do sth 不能干… be able to do sth = be capable of doing
2. unconscious失去知觉的, 未意识到的 He remained unconscious.
I was unconscious of her presence.
3. an understanding mother 通情达理的
have an understanding of = have a knowledge of 对…有所了解
4. undertake 承担 undertake the difficult task He undertook responsibility for this accident.
