  We prove that a nef line bundle $\mathcal L$ with $c_1(\mathcal L)^2 \ne 0$
on a Calabi-Yau threefold $X$ with Picard number $2$ and with $c_3(X) \ne 0$ is
semiample, that is, some multiple of $\mathcal L$ is generated by global
sections.
