be careful with / of the man中用介詞with和of意思不一樣:用
be careful with 表示“對……小心(謹慎)”
be careful of表示“當心或提防”。
be careful in doing 這里的in doing 可以視為時間狀語,意思是“在做某事時”。
be careful to do中的不定式是目的狀語。如:
He is careful in crossing the road. 過馬路時要小心。
He is careful to avoid mistakes. 他很小心,以防出錯。