The ratio of polyploid produced was 87. 5 %, which has shown that crossing combination between Dayali and Pingguoli has special value in pear polyploid breeding.
多倍体出现率为87．5％，表明大鸭梨与苹果梨杂交组合在多倍体育种中具有特殊价值。
2
In this paper, the problem of Crossing Speedily the Changjiang River is analysed, and a type of functional extreme value model is built, then its analysis and elementary solution is illustrated.
对“抢渡长江”问题进行了分析，建立了一种函数极值的数学模型，分析了解题思路和初等求解方法。
3
Companies today confront an increasing array of choices of markets, of locations for value adding activities, and of modes of crossing borders.