8 marbles in a bag, 4 red and 4 white. Randomly get 3 marbles out of the bag, what’s the probability that at least 1 of the 3 marbles is red

封闭母线和插接式母线是分段供货，现场组对连接，完成后要检查总体交流工频耐压水平和绝缘程度。安装前要对各段母线进行绝缘检查，包括各相对的和相间的绝缘检查。( )