1. The observant professor has a remarkable insight into his students' problems and how to solve them.2. In order to make more friends you gotta learn to be more perceptive by reading people's body language and by being a perceptive listener.3. A: Thank you so much for your help. How should I repay you? B: No need. Just be more observant of people and other things in need of your help.
 observant perceptive good at reading people's body languageobservant = 察言觀色，也就是善於觀察身邊的人事物跟環境並做出應對而 perceptive 用來形容人很善於理解人事物，很聰明，能看到其他人看不到的細節，也有察言觀色的意思。good at reading (people's) body language = 「察言觀色」的白話翻譯