—Will you stay for lunch? —Sorry, I ______. My brother is coming to see me. A. mustn’t B. can’t C. needn’t D. wouldn’t 答案:B 如图,在梯形ABCD,AD∥BC,AC⊥BD于点0,AB=DC,AD=3,BC=7,则下列结论:①∠OCB=45°;②S△AOB=S△OCD=214;③S梯形ABCD=25;④AD和BC两平行线间的距离为5,其中正确的有①②③④①②③④.(填入序号).