"In observational studies, we often have to rely on assumptions that are not directly testable."

能源的未来在于传统能源与可再生能源的融合。

滥用权力并不令人惊讶。

But man is not made for defeat. A man can be destroyed but not defeated.

农业的成功始于尊重土地和动物。

过去是幽灵，未来是梦，现在只是转瞬即逝的瞬间。

每个实验都会破坏其开始时的某些条件。