物块 B 中 P=2kN ,物块 A 重 Q=5kN ,在 B 上作用 一水平力 F ,如图所示,当系 A 之绳与水平成 θ=30° 角, B 与水平面间的静滑动摩擦系数 fS1=0.2 ,物块 A 与 B 之间的静滑动摩擦系数 fS2=0.25 ,要将物块 B 拉出时所需水平力 F 的最小值为 ________ 。
【简答题】laugh at; go through; crazy about; on purpose; inorder to; at dusk; face to face; set down; a series of; no longer 1. The camera doesn’t work any longer. So, it is______ used. 2. The workmen ______ th...
【简答题】听句子,选出句子中所包含的信息。 ( )1. A. 116 ( )2. A. this sock ( )3. A. walk into an office ( )4. A. Tom will come here in four months. ( )5. A. Miss. Green had a good time at the party. B. 130 ...
【简答题】完形填空。 Little Tom loves l to stories. His mother 2 him many good stories. Tom thinks many stories always 3 an end. That's not good. One evening little Tom asked his mother to tell him a very, very 4 on...