【单选题】设计滚子从动件盘形凸轮轮廓线时,若将滚子半径加大,那么凸轮理论轮廓线上各点的最小曲率半径()
【简答题】在对某地基土进行试验时,以环刀切取土样。土样 体积 60 cm 3 ,称得原状土样质量为 1 1 6g,烘干后土样质量为 98 g , 测得其比重 G s =2.75。试计算土样的密度 ρ、 含水量 w、 孔隙比 e 和 饱和度 S r 。(10分)
【简答题】(6分) 右图是人们经常使用的交通工具——自行车,请完成下列各题 (1)由金属材料制成的有_________(填序号),属于合成材料的是_________(填序号)。 (2)车轮的钢圈会生锈主要是因为___________,用稀硫酸除铁锈的原理____________(用化学方程式表示)。 (3)利用铁生锈的原理在食品工业上还有应用。“纳米α—Fe粉”,可以用于食品保鲜,称之为“双吸剂...
【单选题】复合材料中纤维增强体应用最广泛的是()纤维。
【单选题】设计滚子从动件盘形凸轮机构的轮廓曲线时,若将滚子半径加大,那么凸轮轮廓线上的各点的曲率半径()
【单选题】在纤维增强体中,( )纤维是应用最为广泛的增强体,可作为树脂基或无机非金属基复合材料的增强材料。
【单选题】Why was the inclusion of Theodore Roosevelt's face on Mount Rushmore so controversial?
A.
His contributions to the development of the country were not important.
B.
The significance of his contributions to U.S. history had not yet been decided.
C.
There were other presidents who had been more influential in politics.
D.
Roosevelt had not been popular with American citizens during his presidency.
【单选题】消化性溃疡根治幽门螺杆菌(Hp)感染的三联药物除外的是
【单选题】He sent me an ______ biography of Theodore Roosevelt which helped me understand American history better.
【单选题】设计滚子从动件盘形凸轮机构的轮廓曲线时,若将滚子半径加大,那么凸轮轮廓线上的各点的曲率半径: