题目

He is in good________for a man of his age. A．condition                       B．atmosphere C．case                            D．situation 答案：A已知直角△ABC，AB=AC=3，P，Q分别为边AB，BC上的点，M，N是平面上两点，若 + =0，（ + ） =0， =3 ，且直线MN经过△ABC的外心，则 =（ ）A.B.C.1D.2