Major banks have been doing well since the worst of the financial crisis shook Wall Street more than a year ago.

VOA: special.2009.12.18

Well, you could think about the cell wall of a bacterium as its skeleton, it's what protects it from mechanical forces that are out in the world.

你可能认为细菌的细胞壁,就像骨骼一样,使其免受,外界机械力的伤害

耶鲁公开课 - 生物医学工程探索课程节选