He began to walk about, looking up in the trees and at the walls and bushes with a thoughtful expression.

他开始四处走动，向上望着树木、墙壁和灌木丛，脸上带着若有所思的表情。

His face took on a thoughtful expression.

他的脸上露出沉思的表情。

She had a thoughtful expression on her face.

她一脸沉思的表情。

I gained a love for words that had little to do with passing school tests and learned that handwriting really was about genuine and thoughtful self-expression.

我失掉一个爱字，并没有通过测试，得知学校笔迹真的是真实的和经过沉思熟虑的自我表现。