parent-offspring relation的用法和样例：
例句
- Sometimes just a few individuals that migrate to an island, thus becoming isolated from the parent species, develop into a new species.
有时，正是移居到某一个岛上的几个个体，由于脱离了它们亲代，因而发育成为一个新种的。 - Mendel deduced that this result was possible only if each individual possesses only two hereditary units, one from each parent.
只有在每个个体仅拥有两个研究遗传单元，并每个单元来自一个亲代时，实验结果才成立。
