1.翻譯"No sooner have we begun talking than you came in."
2.have been doing是現(xiàn)在完成進(jìn)行時(shí),表一個(gè)從過(guò)去持續(xù)到現(xiàn)在的動(dòng)作,強(qiáng)調(diào)進(jìn)行狀態(tài)；have done是已經(jīng)完成.eg：We have been studying here for nearly 3 years. We have studied here since three years ago.
3.現(xiàn)在完成時(shí)的過(guò)去式,通俗地講就是“過(guò)去的過(guò)去”,這時(shí)就用had.eg：In my youth,I had ever been Peking.(只在小時(shí)候的過(guò)去）