$5)$ How many invariants does the strain tensor have? $(5$ scores$)$

A$.$ One

B$.$ Zero

C$.$ Two

D$.$ Three

$6)$ Which of the following factors contribute to displacements of a material point? $(5$ scores$)$

A$.$ Rigid$-$body rotations

B$.$ None

C$.$ Rigid$-$body translations

D$.$ Strain deformations

$7)$ Cauchy stress tensor is symmetric. $(5$ scores$)$

A$.$

B$.$

$8)$ The right and left divergence of the Cauchy stress tensor are $().(5$ scores$)$

A$.$ Negative to each other

B$.$ Anti$-$symmetric to each other

C$.$ Transpose to each other

D$.$ Equal

$9)$ For isotropic elastic materials, Young$$s modulus is $()$ shear modulus. $(5$ scores$)$

A$.$ Not relevant to

B$.$ Less than

C$.$ Equal to

D$.$ Greater than

$10)$ For a simply$-$connected plane domain subjected to harmonic body force potentials and only traction

boundary conditions, which of the following statements are correct? $(5$ scores$)$

A$.$ The stresses for plane strain and plane stress formulations are independent on elastic constants.

B$.$ The stresses for plane strain and plane stress formulations are identical.

C$.$ The Airy stress functions of plane strain and plain stress formulations satisfy the same governing

equation.

D$.$ The displacements for plane strain and plane stress formulations are identical.