be busy with sth
be busy doing sth
knuckle down (to something)
busy or occupied with.
be engaged with
忙于做某事：be busy doing Sth. = be busy with Sth.
例句：I am busy doing my homework.
I am busy with my homework.
是：be busy doing sth
The conviction of the parent was that I should be busy doing more important thingsrather than finding fault with an adolescent's vocabulary.
be busy doing sth./ be busy with sth.
如： He is busy decorating the house.
be busy with/doing sth
be engaged in doing sth
be occupied with sth