be clear about

对…明白，对…明确

be bound for, be bound to, be bound to do, be bound up in, be bound up with, be burned to a crisp, be busy doing, be busy with, be capable of, be careful of, be careful with, be caught up in, be cautious of, be centered on, be central to, be certain of, be certain to do sth, be characteristic of, be charitable to, be civil to, be close to, be committed to doing sth., be comparable to, be comparable with, be composed of, be concerned about, be concerned with, be confronted with, be connected to, be conscious of, be considerate of, be considerate of..., be content with, be contrary to, be convinced that, be covered with, be crazy about, be deep in thought, be deserving of, be detached from,