146 Let the volume of tetrahedron $ABCD$ be $V$, $E$ be the midpoint of edge $AD$, and $F$ be on the extension of $AB$ such that $BF=AB$. The plane through points $C, E, F$ intersects $BD$ at $G$. Then the volume of tetrahedron $CDGE$ is $\qquad$.
$146 \frac{V}{3}$. In $\triangle A F D$, since point $G$ is the intersection of median $B D$ and $E F$, we have $G D=\frac{2}{3} B D . S_{G C D}=$ $\frac{2}{3} S_{B C D}$.
$$
V_{E-\alpha D}=\frac{1}{2} \times \frac{2}{3} V=\frac{V}{3} .
$$