2. If the equation $m x^{2}-2(m+2) x+m+5=0$ has no real roots with respect to $x$, then the number of real roots of the equation $(m-5) x^{2}-2(m+2) x+m=0$ with respect to $x$ is
(A) 2 ;
(B) 1 ;
(C) 0 ;
(D) uncertain.
2. (D)

Solution: Since the first equation has no real roots, its discriminant is
$$
\Delta_{1}=4(m+2)^{2}-4 m(m+5)4$.
For the second equation, when $m>4$ and $m \neq 5$, its discriminant is
$$
\Delta_{2}=4(m+2)^{2}-4 m(m-5)=36 m+16>0 .
$$

It has two distinct real roots; and when $m=5$, the equation becomes a linear equation, which has one real root, thus the number of real roots is uncertain.