从装有3个红球、2个白球的袋中任取3个球,则所取的3个球中至少有1个白球的概率是()。
A.A
B.B
C.C
D.D
参考答案:D
解析:
由典型的概率公式得:[*]
– Were you at school when I called you?
– Yes, I ________ in the library.
A. studied B. am studying C. was studying
在哪种荷载作用下,梁的临界弯距值最低?()
A.跨中集中荷载
B.纯弯曲
C.均布荷载
D.其他