题目

--- I will marry Mike next week.     --- _______. You have only known him for two months. A. That couldn’t be better                B. Congratulations C. That’s a good point                 D. You can’t be serious   答案：D物体在两个相互垂直的力的作用下运动，力F1对物体做功6J，物体克服力F2做功8J，则F1、F2的合力对物体做功为（　　）A．14JB．10JC．2JD．-2J