f

• it constitutes a presheaf of ring on the basis of open sets. (xf)fa .
  这构成了开集基（Xf）fA上的环的予层。
• The function (f')is usually written simply f" and is called the second derivative .
  函数（f’）通常简写成f”，并称之为f的二阶导数。
• This device, which is represented in figure 17.3, consists of six links, a to f .
  图17.3所示即为此种装置，它由自a至f的六根连杆所组成。
• If the mass in question is a plumb bob, the horizontal component of f is important .
  如果所讨论的质量是一摆锤，则重要的是F的水平分量。
• Henceforth, in equation 3-6, the force f is understood to be the parallel component .
  从现在开始，方程（3-6）中的力F应该理解为平行分量。
• It is a fast(f/2. 5), wild-field device, ideal for surveying the night sky .
  它是一个快速（f25）广视场的装置，对于巡视夜空是很理想的。
• If a molecule of net charge q is placed in an electric field, a force f is exerted upon it .
  若将带静电荷q的分子放入电场，则有一个力F作用于其上。
• Baron f was wearing his whole wardrobe dating from the coronation of the emperor francis the first .
  F男爵穿着国王佛兰西斯一世加冕时代的全套衣服。
• Coulomb made the conjecture that electrical force f between two charged objects depends on two factors .
  库仑推测，两个带电体之间的电力F由两个因素决定。