8. There are six measuring cups $A, B, C, D, E, F$, with volumes of $16 \mathrm{~mL}, 18 \mathrm{~mL}, 22 \mathrm{~mL}, 23 \mathrm{~mL}, 24 \mathrm{~mL}$, and $34 \mathrm{~mL}$. Some of the cups are filled with alcohol, some are filled with distilled water, and one cup is empty. The volume of alcohol is twice the volume of distilled water. Therefore, the cups filled with distilled water are ( ).
(A) $B, D$
(B) $D, E$
(C) $A, E$
(D) $A, C$
8.D.

Since $V_{\text {empty }}=2 V_{\text {water }}$, the total volume of the graduated cylinders filled with liquid can be divided by 3. Also, $16+18+22+23+24+34$ leaves a remainder of 2 when divided by 3, so the empty graduated cylinder's volume is 23, which means $D$ is the empty graduated cylinder. Therefore,
$$
V_{\text {water }}=\frac{1}{3}(16+18+22+24+34)=38=16+22 \text {. }
$$

Thus, the graduated cylinders filled with distilled water are $A$ and $C$.