to be engaged in sth or to be engaged on sth
+ activity, discussions, talks, fighting, battles忙于…；参加…；参与…
They found the three engaged in target practice.他们发现那三个人在练习打靶。
the various projects he was engaged on他曾参加过的各个项目
The companies are engaged in advanced discussions.这些公司正在深入讨论。
rebels who have been engaged in fierce fighting with government troops一直与政府军激战的叛乱分子