8. Let $a$ be the integral part of $\sqrt{2}$ and $b$ be its decimal part. Let $c$ be the integral part of $\pi$ and $d$ be the decimal part. If $a d-b c=m$, then ( ).
(A) $-2<m<-1$
(B) $-1<m<0$
(C) $0<m<1$
(D) $1<m<2$
Note: integral part - integer part, decimal part - decimal part
8.A.

The problem states: Given that $a$ and $b$ are the integer and fractional parts of $\sqrt{2}$, respectively, and $c$ and $d$ are the integer and fractional parts of $\pi$, respectively. If $a d - b c = m$, then the range of $m$ is $(\quad$.
(A) $-2 < m < -1$
(B) $-1 < m < 0$
(C) $0 < m < 1$
(D) $1 < m < 2$
Since $a=1, b=\sqrt{2}-1, c=3, d=\pi-3$, we have,
$$
m = a d - b c = \pi - 3 - 3(\sqrt{2} - 1) \approx -1.1 \text{. }
$$