The themes of A Psalm of Life can be concluded as____（）
A. Souls never die
Be optimistic toward life
C. Make the most of life
D. Try to leave footmarks on history
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Which value can be positive, negative, or zero in the geometric properties of the section（）
A. First moments of areas and Moments of inertia
B. Polar moments and Moments of inertia
C. Moments of inertia and Products of inertia
D. First Moments of areas and Products of inertia
Hook’s law holds within the（）
A. Elastic limit
B. Proportional limit
C. Yield limit
D. Strength limit
What is wrong with the following description of internal forces is（）
An internal force is an additional interaction between parts of an object caused by an external force
B. The internal forces are continuously distributed throughout the cross section
C. The internal force varies with the external force
D. An internal force is an interaction between particles in an object
The assumption of deformed solids in material mechanics does not include（）
A. Continuity hypothesis
B. Uniformity hypothesis
C. Isotropic hypothesis
D. Plane hypothesis
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