At common law, contingent remainders and executory interests were not assignable.

在普通法中， 附条件剩余权和待执行权益原本是不可的。

Most rights are freely assignable unless the contract prohibits assignment or the assignment materially alters the obligor's duties.

大多数权利可以自由，除非合同禁止或实质性地改变债务人的务。

He specifies above a dozen characters which may be found varying even on the same branch, sometimes according to age or development, sometimes without any assignable reason.

他指定了十符， 即使在同一分支上也可能发现这些符不同， 有时根据年龄或发展情况， 有时没有任何可指定的原因。

On the other hand, the new facts have brought new powers; man's physical control over natural forces has been increasing with unexampled rapidity, and promises to increase in the future beyond all easily assignable limits.

另一方面，新的事实带来了新的力量；人类对自然力量的物理控制一直在以前所未有的速度增长，并有望在未来增长到超过所有容易指定的限制。