表示【biǎo shì】
1. express; indicate; show 2. express 3. expression; indication
[动] 1、用语言﹑行动显出某种思想﹑感情﹑态度 2、显示某种意义 [名] 3、显示出思想感情的语言、动作或神情

对于朋友们的帮忙,我表示感激。
I should like to thank you for your help.

人们常用红玫瑰表示爱情。
People express their love with roses.

我辛辛苦苦说了半天,她一点儿表示都没有。
Talked as I did, she made no indication at all.
表现【biǎo xiàn】
1. show; display; manifest 2. show (off) 3. behavior; conduct
[动] 1、显露出来 2、故意显示(自己的长处) 3、[名] 从生活、学习、工作等方面反映出来的行为、作风等

他对学业没有表现出多大兴趣。
He doesn't show much interest in his studies.

这人总是喜欢在大伙儿面前故意表现。
The guy likes to show off before us.

自卑是不自信的表现。
Self-contempt is the reflection of lack of confidence.
表演【biǎo yǎn】
1. act; play; perform 2. exhibition; performance
[动] 1、做示范性的动作 [名] 2、戏剧﹑舞蹈﹑杂技等的演出

魔术师表演了一些令人惊叹的戏法。
The magician performed some astonishing tricks.

今晚有芭蕾舞表演吗?
Is there a ballet performance this evening?