精品一区二区免费在线观看_国产精品久久久久久av福利软件_97成人精品区在线播放_国内成人精品一区

I was reading attentively in my own room ________ suddenly he knocked at the door.

I was reading attentively in my own room ________ suddenly he knocked at the door.

A.when B. while  C.then          D. as

I was reading attentively in my own room ________ suddenly he knocked at the door.

I was reading attentively in my own room ________ suddenly he knocked at the door.