【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______.
【单选题】下述哪些说法是错误的()
B.
SCM实现了产品供应的合理性、高效性和高弹性
D.
SCM是在ERP基础上构筑的与客户及供应商的互动系统
【多选题】下述哪些说法是错误的
C.
凡有免疫原性的抗原物质的分子量一般在1万以上
【单选题】The bound morphemes include two types: ________ and _________.
【单选题】Which of the following words is made up of bound morphemes only
【单选题】The following underlined suffixes are bound morphemes except ( )
【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】Which of the following are NOT bound morphemes?
【简答题】The morphemes can be grouped into ____morphemes and bound morphemes.