Which of the following statements about crystal systems are correct?

1. AThere are seven Bravais lattices in total.
2. BIn a trigonal (rhombohedral) system $a=b=c$ and $\alpha =\beta =\gamma \ne 90^{\circ }$.
3. CIn a monoclinic system $a\ne b\ne c$, $\alpha =\gamma =90^{\circ }$ and $\beta \ne 90^{\circ }$.
4. DIn a hexagonal system $a=b\ne c$, $\alpha =\beta =90^{\circ }$ and $\gamma =120^{\circ }$.