直插法
参考答案：
也称叶柄插法，将叶柄插入沙中。（非洲紫罗兰、豆瓣绿、球兰、虎尾兰、椒草）
二手船舶交易中，如采用公开拍卖方式成交，则买方一般处于比较被动的位置，因为其一般只能按照船舶现状进行交接而不能和卖方就船舶技术条件和商务条件进行谈判。
Of the science books in a certain supply room, 50 are on botany, 65 are on zoology, 90 are on physics, 50 are on geology, and 110 are on chemistry. If science books are removed randomly from the supply room, how many must be removed to ensure that 80 of the books removed are on the same science ？（）
A．81
B．159
C．166
D．285
E．324
