【单选题】给出下列条件(其中l和a为直线,α为平面): ①l垂直α内一凸五边形的两条边; ②l垂直α内三条都不平行的直线; ③l垂直α内无数条直线; ④l垂直α内正六边形的三条边; ⑤a垂直α,l垂直a. 其中是“l垂直α”的充分条件的所有序号是( )
【单选题】Why did some TT therapists agree to be the subject of Emily's experiment?
A.
Each participator would be offered more than $1 million as reward.
B.
They thought the girl was too young to make any meaningful discovery.
C.
The experiment was more straightforwardly participated than other experiments.
D.
They took the experiment as an interesting rather than a scientific practice.
【单选题】曲线积分 ( ),其中L为沿直线从点 到点 ,再沿直线到 的折线.
【简答题】在空间中,取直线l为轴,直线l′与l相交于点O,其夹角为α(α为锐角),l′围绕l旋转得到以O为顶点,l′为母线的圆锥面,任取平面π,若它与轴l交角为β(π与l平行时,记β=0),则:当 π 2 >β>α 时,平面π与圆锥面的交线为______.
【单选题】The purpose of Emily Rosa% experiment was ______.
A.
to see why TT could work the way it did
B.
to find out how TT cured patients' illness
C.
to test whether she could sense the human energy field
D.
to test whether a human energy field really existed
【单选题】Why did some TT practitioners agree to be the subjects of Emily's experiment?
A.
It involved nothing more than mere guessing.
B.
They thought it was going to be a lot of fun.
C.
It was more straightforward than other experiments.
D.
They sensed no harm in a little girl's experiment.
【简答题】Why did Miss Emily kill Homer Barron?
【单选题】令A为小于10的正奇数集合,则|A|=( )。