pain是疼痛的意思,而sadness则是悲伤的意思,区别可以从以下例子看出:
He is suffering from long-term pain in his joints, make him look so sadness. But we can't do anything, that's life. 他的关节长期疼痛,让他看起来很悲伤。 但我们什么也做不了,这就是生活。
pain的意思是痛苦,痛觉。sadness的意思是悲伤。
这些词的规律是:名词+词尾ful= 形容词pain+ful= painfulhurt+ful= hurtful