單項(xiàng)選擇題

(2006)如圖所示,直桿受扭轉(zhuǎn)力偶作用,在截面1—1和2—2處的扭矩為:()

A.5kN·m,5kN·m
B.25kN·m,-5kN·m
C.35kN·m,-5kN·m
D.-25kN·m,25kN·m