1、In some plant species, intersterile varieties may exist, which means they cannot cross-pollinate and produce viable offspring.
在某些植物物种中，可能存在不能进行交叉授粉并产生能繁殖的后代的不育变种。
2、The intersterile nature of these two animal species has hindered efforts to create hybrids in the laboratory.
这两种动物物种无法相互交配的特性阻碍了在实验室中创造混合种的努力。