题目

--- Tom is fond of surfing the Internet and junk food.    --- Well, ___________. But I’ve realized it’s really bad.     A. so am I.    B. so do I    C. so I am   D. nor am I 答案：A在ABCD中，点E、F分别在AB、CD上，且AE=CF．（1）求证：△ADE≌△CBF；（2）若DF=BF，求证：四边形DEBF为菱形．