题目

找出相应的答语⑴Good evening, Helen!A.Good morning, Cindy!⑵Good morning, Dale! B. Good afternoon, Eric!⑶Good afternoon, Frank! C.Good evening, Bob!⑷Hi, Tina! D. Fine, thanks. ⑸How are you? E. Hi. Dale! 答案：【1】C【2】A【3】B【4】E【5】D已知：在梯形ABCD中，AD∥BC，AB=CD=6，上底AD=4，∠B=60°，则下底BC=    ．