— Why are you crying?
— Because I my finger.[ ]
A. hurts
B. hurt
C. am hurting
答案:B
美感的直觉的特点
结构如图,折杆AB与直杆BC的横截面面积为A=42cm2,Wy=Wz=420cm3,[σ]=100MPa,则此结构的许可荷载[P]为:()
A.15kN
B.30kN
C.45kN
D.60kN