忙于做某事的英文短语有：be busy （in） doing sth，be busy with sth。
1、例句：The conviction of the parent was that I should be busy doing more important things rather than finding fault with an adolescent'。
忙于某事：be busy doing sth 英语中的 be busy doing sth 是一个常用搭配，比如：He is busy writing，他正忙于写作。
I’m busy cooking the dinner，我正忙着烧饭。
She was busy weeding the garden，她在花园里忙。
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.我忙于做作业。
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.我忙于做作业.