(1) Given that $\mathrm{i}$ is the imaginary unit, then the complex number $\frac{1+2 \mathrm{i}}{\mathrm{i}-2}=(\quad$.
(A) i
(B) $-\mathrm{i}$
(C) $-\frac{4}{5}-\frac{3}{5} \mathrm{i}$
(D) $-\frac{4}{5}+\frac{3}{5} \mathrm{i}$
(1) $B$ Hint: $\frac{1+2 \mathrm{i}}{\mathrm{i}-2}=\frac{(1+2 \mathrm{i})(\mathrm{i}+2)}{(\mathrm{i}-2)(\mathrm{i}+2)}=-\mathrm{i}$.