Did you notice him come into the hall?Sorry sir. I with my friends online.A. was

问题补充：

--- Did you notice him come into the hall?

--- Sorry, sir. I with my friends online.

A. was chatting

B. chatted

C. would chat

D. am chatting

答案：

(答案→)A. was chatting

B. chatted

C. would chat

D. am chatting

解析：句意：你注意到他进入大厅了吗？——抱歉，先生。我（当时）正在和我的朋友在线聊天。结合语境可知下文描述的是过去某时正在进行的动作，故用过去进行时态。选A。