She looks up now，catching me 27　　 at her, causing her to say to her mother." Mom, Dad’s looking at me 28　　 .”

　 The last few days，I touch her arm，her face一anything- 　29　　 that when my wife and I return home，she will not be with and there will be nothing to30　　 ．I have so much to say, but no31　　 with which to say it

　　 My32　　 changed from the day I drove this child home from the hospital. I saw myself33　　 that day, and it has led to a lot of places that I would never have found on my own .

　　 She says，“It'll be all right，Dad．I’ll be home from school 34　　 .”I tell her she will have a great year but I say little else．I am afraid somehow to speak and I only hold on to our good-bye hug a little longer, a little35　　 .

I gaze into her eyes and 36　　 to go. My wife’s eyes follow her as she leaves us.37　　 do not．Maybe if I don’t look，I can imagine that she really hasn’t38　　 ；I know that what she is embarking upon (開始)is exciting and wonderful．I remember what the world looked like to me39　　 everything was new.

　　 As I walk to the car with my wife at my side，my eyes are wet，my heart is sore，and I realize that my life is 40　　 forever．

21．A．sister’s 　　　　　　　 B．teacher's　 　　　　　 C．mother's　 　　　　　 D．roommate's

11． 一條長為的線段夾在互相垂直的兩個平面、之間，AB與所成角為，與所成角為，且，，，、是垂足，求(1)的長；(2)與所成的角

10．在三棱臺中，側棱⊥底面，且，．

(1)求證：，，．

(2)求異面直線和的距離．

9．已知不共面的三條直線、、相交于點，，，，，求

8．兩條異面直線、間的距離是1cm，它們所成的角為60⁰，、上各有一點A、B，距公垂線的垂足都是10cm，則A、B兩點間的距離為____________________．

7．在棱長為的正四面體中，相對兩條棱間的距離為________________．

6．在正三棱柱中，若，則與所成的角的大小　　 ．　

5．已知異面直線a與b所成的角為50⁰，P為空間一點，則過點P與a、b所成的角都是30⁰的直線有且僅有(　　　 )

1條　　　　 2條　　　　　 3條　　　　　　 4條

4．已知直線a，如果直線b同時滿足條件：①a、b異面②a、b所成的角為定值③a、b

間的距離為定值，則這樣的直線b有(　　　　 )

1條　　　　 2條　　　　　 4條　　 　　　　無數(shù)條

3．AB、CD在平面α內(nèi)，AB//CD，且AB與CD相距28厘米，EF在平面α外，EF//AB，且EF與AB相距17厘米，EF與平面α相距15厘米，則EF與CD的距離為(　　 )

25厘米　　　 39厘米　　　 25或39厘米　　 15厘米