He walked most slowly of the three.

在三个人中他走得最慢。

He walked the most slowly of them all.

他们当中，他走得最慢。

It is probably the plant which grows the most slowly.

这也许是植物里生长速度最慢的一种了。

Walk the most slowly, as long as he doesn't lose target than aimless wandering people walk fast.

走的最慢的人，只要他不丧失目标，也比漫无目的徘徊的人走得快。

That's because, at our farthest from the sun, like now, Earth is traveling most slowly in its orbit.

这是因为，像现在离太阳最远，地球在它的轨道运行最慢。