观其行的英文：
observing one's conduct

参考例句：

A tree is known by its fruit
观其行而知其人

A tree is known by its fruit
观其行而知其人

A tree is known by its fruit
观其行而知其人

Words are to be judged from their function; and deeds are to be observed form their effects
听其言必责其用,观其行必求其功

observing是什么意思：
adj. 观察力敏锐的；观察的；注意的
v. observe的现在分词；观察

We observed the barometer fall. [The barometer was observed to fall.]
我们看见晴雨表下降。

Observation is the best teacher.
观察是最好的老师。

They observed the behavior of their new pet.
他们观察他们新宠物的生活习性。

one是什么意思：
num. 一；同一个、最重要的一个
det. 代替a或an，表示强调；某位（用于不太熟悉之人的姓名之前）
pron. 任何人；一个人；一个事物；其中的一个人

One, Taipei, one way.
台北单程票一张。

This one is not a spoof.
这个就不是开玩笑了。

One and one make(s) two.
一加一等于二。

conduct是什么意思：
n. 举止；行为；品行
v. 表现；处理；管理；实施

Their conduct and etiquette are governed by the Code of Conduct for the Bar of the HKSAR.
律师的操守和业内成规，受香港大律师公会专业守则所约束。

The reporter was accused of unprofessional conduct.
那位记者被控有违反职业道德的行为。

Such conduct will compromise your reputation.
这些举动将会损害你的名誉。