7. 點從點出發(fā)，按逆時針方向沿周長為的圖形運動一周，兩點連線的距離與點走過的路程的函數(shù)關(guān)系如圖，那么點所走的圖形是（   ）

A.    B. ,     C.   D. ,

6.若函數(shù)的導數(shù)是則函數(shù) (0<a<1)的單調(diào)遞減區(qū)間是(   )                                                                                                                                                                                                                                                                      

5.若直線mx+ny=4和圓O:沒有交點,則過點(m,n)的直線與橢圓的交點個數(shù)為(   )

 A.至多一個         B.2個         C.1個            D.0個

4.甲、乙、丙、丁、戊5人站成一排，要求甲乙均不與丙相鄰，不同排法種數(shù)有  （  ）

 A. 72            B.54                 C.36            D.24

  C. 且                D. 且

A. 且               B. 且

3.直線與平面滿足,,那么必有 (    )

A.          B.                  C.           D.1

2.與復數(shù)的積為1的復數(shù)的虛部為                      (    )