7. For $\triangle \mathrm{ABC}$ with sides $\mathrm{a}, \mathrm{b}, \mathrm{c}$, the heights to these sides are $\mathrm{h}_{\mathrm{s}}=6$, $\mathrm{h}_{\mathrm{b}}=4, \mathrm{~h}_{0}=3$. Then the ratio of the sides $\mathrm{a}: \mathrm{b}: \mathrm{c}$ is:
(A) $1: 2: 3$;
(B) $2: 3: 4$,
(C) $3: 4: 6$;
(D) Uncertain.
笭: $(\mathrm{B})$.
From $a h_{2}=b h_{b}=c b_{0}$, we can find that $a: b: c=2: 3: 4$.