【单选题】以下各力系中,有两个独立平衡方程的是()。 (A)平面一般力系 (B)平面力偶系 (C)平面平行力系 (D)空间汇交力系
【单选题】If Stephanie buys a laptop for $700 and the maximum she would have paid was $1,000, which of the following is true?
A.
Stephanie received consumer surplus of $1,000.
B.
Stephanie received producer surplus of $700.
C.
Stephanie received a consumer surplus of $700.
D.
Stephanie received a consumer surplus of $300.
【多选题】物体在平面平行力系的作用下,今选择 y 轴与力系各力平行, x 轴与力系各力垂直,其独立的平衡方程数目只有两个,为( )。
【单选题】下列不属于苏门四学士的是( )。 prefix="o" ns="urn:schemas-microsoft-com:office:office" ?xml:namespace>