题目

When I was in Germany, one day at Christmas-time I went to a post office to send a letter. To my (41)______ I found people queuing some paces away from the person at the savings deposit window. (42)_____so? Each did his business (43)_____ but the line never moved a step (44)_____. I was very (45)____, so I walked to the window to find out the cause. There was a notice on which was written “Thank you for your (46)_____for other's privacy”—a polite (47)_____to keep people away from nosing into other's (48)_____ (money matters are regarded as privacy in Western countries). I was de如果一个数的立方为64，则这个数的平方根是    ．