His condition got worse. In nineteen fifty-four, Woody Guthrie traveled one more time across America.

VOA: special.2010.06.20

I differentiate a second time and check the sign, so the second order condition, I differentiate this expression again with respect to q1.

我们对它进行二次求导然后看符号,这个式子的二阶导数,就是一阶导数再对q1进行求导

耶鲁公开课 - 博弈论课程节选

It's actually better to spend a certain amount of time just keeping your body in good condition

其实花一定时间保持身体的良好状态更好，

健康生活 - SpeakingMax英语口语达人