Class preserving automorphisms of some nilpotent groups of class 2

An automorphism $\alpha$ of a group $G$ is called a class preserving automorphism if $\alpha(g)$ and $g$ are conjugate in $G$ for each $g \in G$. We prove that each class preserving automorphism of the following nilpotent groups of class 2 is inner:
(i) The direct product of a generalized extraspecial $\mathbb{Z}$-group and a free abelian group with finite rank.
(ii) An extension of $\mathbb{Q}$ by a direct sum of finitely many copies of $\mathbb{Q}$, where $\mathbb{Q}$ is the additive group of rational numbers.
(iii) An infinite Černikov $p$-group which is not abelian but each proper quotient group is abelian.