At that age， I'd take any excuse to make estimates and do minor arithmetic. I'd calculate our gas mileage -- figure out useless statistics on things like grocery spending. I'd been hearing an ad campaign about smoking. I can't remember the details， but basically the ad said， every puff of a cigarette takes some number of minutes off of your life: I think it might have been two minutes per puff. At any rate， I decided to do the math for my grandmother. I estimated the number of cigarettes per days， estimated the number of puffs per cigarette and so on. When I was satisfied that I'd come up with a reasonable number， I poked my head into the front of the car， tapped my grandmother on the shoulder， and proudly proclaimed， "At two minutes per puff， you've taken nine years off your life！"

"The more we learn, the more we realize how much we don't know."

We must strengthen international cooperation to jointly address the challenges of energy security and climate change.

恐惧无时无刻地在我们耳边窃窃私语、在我们眼前高声呐喊；而信念必须由你们每天在镜中看到的自己培养。前者总是紧追在我们身后、纠缠不休、令我们停滞不前；后者则激励我们、带给我们惊喜、刺激我们的创造力、驱使我们不断地前进。

Winning is not always the barometer of getting better.