回復 1# thankyou 的帖子
(A)、(D)是錯的，反例：\(a=1,b=-3,c=-1\)
\(\begin{align}
& a+b+c<0,\left| a+b \right|+c>0 \\
& a+b<-c<\left| a+b \right| \\
& a+b<0 \\
\end{align}\)
(C)正確
\(\begin{align}
& \left| a+b \right|+c>0,\left| a \right|+b+c<0 \\
& \left| a \right|+b<-c<\left| a+b \right|\le \left| a \right|+\left| b \right| \\
& b<0 \\
\end{align}\)
(E)正確
\(\begin{align}
& (1)\ a+b<-c<0 \\
& \left| a \right|+\left| b \right|\ge \left| a+b \right|>\left| -c \right|=\left| c \right| \\
& \left( 2 \right)\ a+b<0<-c<\left| a+b \right| \\
& \left| a \right|+\left| b \right|\ge \left| a+b \right|>\left| -c \right|=\left| c \right| \\
\end{align}\)
(B)正確
