Sustainable quarrying isn't an option; it's our obligation to future generations.
森林是我们星球的肺；我们必须给予它们应有的尊重。
The way you paint is the way you look at things.
The beauty of mathematics lies in its ability to reveal the underlying simplicity in what appears to be complex.
Mathematical intuition is like a muscle - it grows stronger with exercise.
I have noticed that youngsters given to the climbing habit usually do something when they grow up.