【简答题】重力为400N的木箱放在水平面上,木箱与地面的最大静摩擦力是120N,动摩擦因数为0.25.如果分别用70N和150N的水平力推木箱,设最大静摩擦力和滑动摩擦力相等,则木箱受到的摩擦力分别是____ N和 ____ N 。
【简答题】一个大木箱原放在水平地面上.如图所示,现某人将它装在重为50N的小车将它从斜面底端沿斜面匀速推上顶端,整个过程历时10秒.已知木箱重400N,人对车的推力F=75N,斜面长4m,斜面高0.5m,人做功的功率______W;人做的有用功______J;人做的总功______J;斜面的机械效率为______.
【简答题】I like the style of the book, but I don’t like its ____(内容 ).
【判断题】'Affix hopping refers to the bound morphemes in the verb group hop backward to join the following member in the verb group .()
【单选题】The bound morphemes include two types: ________ and _________.
【判断题】All the free morphemes are lexical morphemes and all the bound morphemes are grammatical morphemes.
【单选题】I like the style of his writing but I don'tt like the ________.
【简答题】(a)List the bound morphemes to be found in the following words; misleads, shortened, unhappier, fearlessly (b)In which of the following examples should the a be treated as a bound morpheme: a boy, app...
【单选题】重为 400N 的木箱放在水平地面上,木箱与地面间的最大静摩 擦 力是 120N ,动摩擦因数是 0 . 25 ,如果用 70N 的 水平力推木箱,木箱受到的摩擦力是( )N。
【简答题】重为 400N 的木箱放在水平地面上,木箱与地面间的最大静摩 擦 力是 120N ,动摩擦因数是 0 . 25 ,如果用 70N 的 水平力推木箱,木箱受到的摩擦力是 , 如果用 150N 的水平力推木箱,木箱受到的摩擦力是 。