设空间区域 $\Omega_1: x^2+y^2+z^2 \leq R^2, z \geq 0 ; \quad \Omega_2: x^2+y^2+z^2 \leq R^2, x \geq 0, y \geq 0, z \geq 0$, 则
A
$\iiint_{\Omega_1} x d V=4 \iiint_{\Omega_2} x d V$.
B
$\iiint_{\Omega_1} y d V=4 \iiint_{\Omega_2} y d V$.
C
$\iiint_{\Omega_1} z d V=4 \iiint_{\Omega_2} z d V$.
D
$\iiint_{\Omega_1} x y z d V=4 \iiint_{\Omega_2} x y z d V$.
E
F