6. If the equation $(m+2) x^{2}-2(m+1) x+m=0$ has only one real root, then the equation $(m+1) x^{2}-2 m x+m-2=0$ ( . ).
(A) has no real roots
(B) has two distinct real roots
(C) has two equal real roots
(D) the number of real roots cannot be determined
6. C. (Hint: The discriminant of the original equation is $\Delta=4(m+1)^{2}$ $-4 m(m+2)=4>0$, the equation has only one root, so the coefficient of the quadratic term is 0, i.e., $m+2=0, m=-2$. )