由四舍五入法得到的近似数9.2×102有效数字的个数是 [ ]
A.3
B.2
C.1
D.以上都不对
答案：B
用狭平板钢板，螺旋卷成并焊接成截面为圆形，外径50cm的石油管道
What of the following statements is NOT true about Chuck Feeney a. He is mean toward other people. b. He lives a very economical life. c. He is charitable. d. He is rich.
