-------in conversation,they didn't notice me entering the ro

选 1.engaged
Engaged in conversation,they didn't notice me entering the room.他们忙着说话,都没注意我进屋了.
engaged 形容词,从事...的;忙於...的[(+in/on)],后面不用加反身代词,所以2,3,4都不对.
例如:
He is engaged in his business.
他忙於他的生意.
We are engaged in compiling a dictionary.
我们正忙於编一本字典.
She was engaged in protecting wild birds.
她致力於保护野生鸟类的工作.
She is now engaged in writing letters.
她现在正忙著写信.