At the same time, by enlarging the sourceofparents and adopting composite crosses, the defects of low genetic variability and genetic uniformity of low gossypol cotton can be overcomed.
同时，采用拓展亲本来源、复合杂交等手段，克服了低酚棉遗传变异率低，以及遗传单一的弊端。
2
For parents, their children's enrollment is a sourceof joy and pride.
对父母来说，他们的孩子去上大学也是他们快乐和自豪的源泉。
3
These exceptions are the sourceof endless frustration for the parents of the vast majority of children who develop the ability to read at a typical rate.