To signal an emergency, use the rule of three; 3 shouts, 3 horn blasts, or 3 whistles.
数学不是关于数字、方程、计算或算法的:它是关于理解的。
"Gratitude can transform common days into thanksgivings, turn routine jobs into joy, and change ordinary opportunities into blessings."
梦想是让我们继续前行的力量,即使一切似乎都已失去。