摘要
1.0观察下列两组句子:[1]We have known each other since I came here.[2]We have known ench other since I was here.[3]He has written to me frequently since I have been ill.[4]He has written to me frequently since I was ill.
出处
《解放军外国语学院学报》
1987年第2期29-33,共5页
Journal of PLA University of Foreign Languages