【单选题】Jeff tried to wrestle him to the ground, but Weise stubbornly held his own.
【简答题】已知抛物线C:y 2 =4x的焦点为F,直线l过点F且其倾斜角为45°,设直线l与曲线C相交于A、B两点,求以线段AB为直径的圆的标准方程.
【判断题】100405激活脊髓前角γ运动神经元,可以增加肌梭的传入冲动。
【单选题】What is the relationship between Jeff May and Jeff Weise?
A.
Jeff May and Jeff Weise were brothers.
B.
Jeff May and Jeff Weise shared a room.
C.
Jeff May and Jeff Weise both had a crush on Alicia White.
D.
Jeff May knew Jeff Weise but they never talked.
【单选题】在电阻性负载单相桥式半控整流电路中,直接输入220伏50Hz交流电压,RL=5Ω。问当导通角为90°时,输出电压( )V和输出电流的平均值是( )A?
【简答题】在法律部门的相互关系上,民法是普通法或基本法,商法是 。
【判断题】因为缺少替代品,对食盐的需求就是缺乏弹性的。( )
【单选题】What is the relationship between Jeff May and Jeff Weise?
C.
Both of them had a crush on Alicia White.
D.
Jeff May knew Jeff Weise but they never talked.
【简答题】(12 分)已知椭圆 ,直线l与椭圆交于A、B两点,M是线段AB的中点,连接OM并延长交椭圆于点C.直线AB与直线OM的斜率分别为k、m,且 . (Ⅰ)求 的值; (Ⅱ)若直线AB经过椭圆的右焦点F,问:对于任意给定的不等于零的实数k,是否存在a∈ ,使得四边形OACB是平行四边形,请证明你 的结论;
【简答题】如图,已知直线l与⊙O相离,OA⊥l于点A,OA=5,OA与⊙O相交于点P,AB与⊙O相切于点B,BP的延长线交直线l于点C。 (1)试判断线段AB与AC的数量关系,并说明理由; (2)若PC= ,求⊙O的半径和线段PB的长; (3)若在⊙O上存在点Q,使△QAC是以AC为底边的等腰三角形,求⊙O的半径r的取值范围。