苋菜是人们常见的蔬菜,炒苋菜时汤会变红,其红色物质主要来自细胞内的哪一结构
A:细胞质
B:细胞核
C:细胞膜
D:液泡
计算
10-0.47-0.12-0.41=____
He never __________ to help those in trouble because he was a kind-hearted man.( )