The challenge in computer science is not just to solve problems, but to understand why they are problems in the first place.
美国农民是我们经济中唯一必须以零售价购买所需一切,以批发价出售所产一切,并支付双向运费的人。
"The only limit to our realization of tomorrow is our doubts of today."
可持续发展不再是选择,而是生存的必需。