在10个球中,有6个红球和4个白球(除编号外其它完全相同),不放回地依次摸出2个球,在第一次摸出红球的条件下,第二次也摸出红球的概率为_____
5/9
—Can I get my ears pierced, Mom?
—No. As a student, you _____ do that. [ ]
A. are allowed to
B. should be allowed to
C. may not
D. shouldn't be allowed to
臂架型起重机除了有起升机构外,通常还有大车运行、小车运行和回转机构。