1、busy是形容詞和動詞。作為形容詞可以用作定語說明被修飾詞所具有繁忙的特征，用作表語說明主語具有的特征或所處的狀態。作為動詞，表示“使行為者忙於某項事情”或“行為者奔走於某項活動”。如：
a busy Sunday 壹個忙碌的星期天定語
a busy street 壹條熱鬧的街道定語
She is busy in another's affair. 她喜歡幹涉別人的事表語
I am busy with my professional paper. 我忙於寫專業論文。表語
She said she would be too busy to come. 雷切爾說她太忙，不會來了。表語
He busied himself with the camera. 他忙著擺弄那個相機。謂語動詞
I busied about and made him some sandwiches. 我忙了壹陣子給他做了幾塊三明治。謂語動詞
2、busily 是副詞，用作狀語，說明動詞的繁忙程度。如：
The doctor worked busily beneath the blinding lights of the delivery room. 這位醫生在產房刺目的燈光下忙碌著。說明 worked 的程度
The two saleswomen were busily trying to keep up with the demand. 那兩名女售貨員正忙著接待顧客。說明 trying tokeep up 的程度