3. Calculate:
$$
4 \times(-1+2-3+4-\cdots+1000)=(\quad) \text {. }
$$
(A) -10
(B) 0
(C) 1
(D) 500
(E) 2000
3. E.

Notice,
$$
\begin{array}{l}
4 \times(-1+2-3+4-\cdots+1000) \\
=4[(-1+2)+(-3+4)+\cdots+(-999+1000)] \\
=4 \times(\underbrace{1+1+\cdots+1}_{500 \uparrow})=2000 .
\end{array}
$$