1.65 In the range of real numbers, the value of $\left|1 \sqrt{-x^{2}}-1\right|-2 \mid$ is
(A) cannot be determined.
(B) can only be 3.
(C) can only be 1.
(D) none of the above answers is correct.
(China Guangzhou, Wuhan, Fuzhou and other five cities junior high school mathematics competition, 1986)
[Solution] According to the problem, if $\sqrt{-x^{2}}$ is meaningful, it is only when $x=0$. Therefore, $|\sqrt{-x^{2}}-1|-2|=|1-1|-2|=1$. Hence, the answer is $(C)$.