1. [ $x$ ] represents the greatest integer not greater than $x$, and $\{x\}$ $=x-[x]$. Then, among the following relations, the incorrect one is ( ).
(A) $[\sqrt{45}]=6$
(B) $\{\sqrt{45}\}=\sqrt{45}-6$
(C) $[-\sqrt{45}]=-6$
(D) $\{-\sqrt{45}\}=7-\sqrt{45}$
- 1.C.

Since $-7<-\sqrt{45}<-6$, therefore,
$$
[-\sqrt{45}]=-7 .
$$