fragile adj. 易碎的，脆的
例句：Glasses are fragile and must be handled with great care.
玻璃制品易碎，必须小心轻放。

fragments n．碎片，断片，片段
例句：Carry dropped the vase on the floor and it broke into fragments.
凯丽把花瓶掉在地上，摔成了碎片。

fraction n．小部分，片断，分数
例句：She has done only a fraction of her homework.
她只做了家庭作业的一小部分。

friction n. 摩擦，摩擦力
例句：Friction against the rock combined with the weight of the climber, caused his rope to break.
与岩石之间的摩擦加上攀登者的重量，使得绳子断了。

fracture n. 破裂，骨折 v. （使）破碎，（使）破裂
例句：Fracture of the leg can be very serious in elders.
老年人腿骨骨折有可能成为严重疾患。