It's so much darker when a light goes out than it would have been if it had never shone.
"Every failure is a stepping stone to success, provided we learn from it."
检验统计假设的问题是估计的一般问题中不可分割的一部分。
安全生产是煤炭行业的生命线,任何时候都不能放松。
Mental processes are means to ends in the struggle for existence.
A physical symbol system has the necessary and sufficient means for general intelligent action.